NISTIR 7880-30 

NIST Micronutrients Measurement 

Quality Assurance Program 

Winter, Spring, and Fall 1994 

Comparability Studies 

Results for Round Robins XXX, XXXI, and XXXII 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robins 5 and 6 Ascorbic Acid in Human Serum 

David L. Duewer 

Margaret C. Kline 

Sam A. Margolis (Retired) 

Katherine E. Sharpless 

Jeanice B. Thomas 

http://dx.doi.org/10.6028/NIST.IR.7880-30 

 

 

 

 

 

 

NISTIR 7880-30
 

NIST Micronutrients Measurement 

Quality Assurance Program 

Winter, Spring, and Fall 1994 

Comparability Studies 

Results for Round Robins XXX, XXXI, and XXXII 

Fat-Soluble Vitamins and Carotenoids in Human Serum 

and Round Robins 5 and 6 Ascorbic Acid in Human Serum 

David L. Duewer 

Sam A. Margolis (Retired) 

Katherine E. Sharpless 

Jeanice B. Thomas 

Chemical Sciences Division 

Materials Measurement Laboratory 

Margaret C. Kline 

Biomolecular Measurement Division 

Material Measurement Laboratory 

http://dx.doi.org/10.6028/NIST.IR.7880-30 

November 2014 

U.S. Department of Commerce 

Penny Pritzker, Secretary 

National Institute of Standards and Technology 

Willie E. May, Acting Under Secretary of Commerce for Standards and Technology and Acting Director 
(This page intentionally blank) 

ii
 
 

 

 

 

 

 

 

 

Abstract 

The National Institute of Standards and Technology coordinates the Micronutrients Measurement 

Quality Assurance Program (MMQAP) for laboratories that measure fat- and water-soluble vitamins 

and carotenoids in human serum and plasma. This report describes the design of and results for the 

Winter, Spring and Fall 1994 MMQAP measurement comparability improvement studies: 1) Round 

Robin XXX Fat-Soluble Vitamins and Carotenoids in Human Serum, 2) Round Robin XXXI FatSoluble Vitamins and Carotenoids in Human Serum, 3) Round Robin XXXII Fat-Soluble Vitamins 

and Carotenoids in Human Serum, 4) Round Robin 5 Ascorbic Acid in Human Serum, and 5) Round 

Robin 6 Ascorbic Acid in Human Serum. The materials for Round Robin XXX were shipped to 

participants in January 1994; participants were requested to provide their measurement results by 

March 19, 1994. The materials for Round Robin XXXI were shipped to participants in April 1994; 

participants were requested to provide their measurement results by July 25, 1994. The materials for 

Round Robin XXXII were shipped to participants in July 1994; participants were requested to 

provide their measurement results by August 30, 1994. The sample materials for Round Robin 5 

were distributed in April 1994 with results due by May 31, 1994. The sample materials for Round 

Robin 6 were distributed in August 1994 with results due by September 30, 1994. 

Keywords 

Human Serum 

Retinol, α-Tocopherol, γ-Tocopherol, Total and Trans-β-Carotene 

Ascorbic Acid 

iii 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table of Contents 

Abstract............................................................................................................................................... iii
 

Keywords ............................................................................................................................................ iii
 

Table of Contents ............................................................................................................................... iv
 

Introduction......................................................................................................................................... 1
 

Round Robin XXX: Fat-Soluble Vitamins and Carotenoids in Human Serum .......................... 1
 

Round Robin XXXI: Fat-Soluble Vitamins and Carotenoids in Human Serum......................... 2
 

Round Robin XXXII: Fat-Soluble Vitamins and Carotenoids in Human Serum ....................... 2
 

Round Robin 5: Vitamin C in Human Serum................................................................................. 3
 

Round Robin 6: Vitamin C in Human Serum................................................................................. 3
 

References ............................................................................................................................................ 4
 

Appendix A. Shipping Package Inserts for RR30........................................................................ A1
 

Appendix B. Final Report for RR30 ..............................................................................................B1
 

Appendix C. “All-Lab Report” for RR30 ......................................................................................C1
 

Appendix D. “Individualized Report” for RR30 ......................................................................... D1
 

Appendix E. Shipping Package Inserts for RR31 ......................................................................... E1
 

Appendix F. Final Report for RR31............................................................................................... F1
 

Appendix G. “All-Lab Report” for RR31...................................................................................... G1
 

Appendix H. “Individualized Report” for RR31 .......................................................................... H1
 

Appendix I. Shipping Package Inserts for RR32 ........................................................................... I1
 

Appendix J. Final Report for RR32 ................................................................................................ J1
 

Appendix K. “All-Lab Report” for RR32..................................................................................... K1
 

Appendix L. “Individualized Report” for RR32........................................................................... L1
 

Appendix M. Shipping Package Inserts for RR05 ....................................................................... M1
 

Appendix N. Final Report for RR05 ............................................................................................. N1
 

Appendix O. “All-Lab Report” for RR05..................................................................................... O1
 

Appendix P. Shipping Package Inserts for RR06 ......................................................................... P1
 

Appendix Q. “All-Lab Report” for RR06..................................................................................... Q1
 

iv 
 

 

 

Introduction 

Beginning in 1988, the National Institute of Standards and Technology (NIST) has coordinated the 

Micronutrients Measurement Quality Assurance Program (MMQAP) for laboratories that measure 

fat- and water-soluble vitamins and carotenoids in human serum and plasma. The MMQAP 

provides participants with measurement comparability assessment through use of interlaboratory 

studies, Standard Reference Materials (SRMs) and control materials, and methods development and 

validation. Serum-based samples with assigned values for the target analytes (retinol, alphatocopherol, gamma/beta-tocopherol, trans- and total beta-carotene, and ascorbic acid) and 

performance-evaluation standards are distributed by NIST to laboratories for analysis. 

Participants use the methodology of their choice to determine analyte content in the control and 

study materials. Participants provide their data to NIST, where it is compiled and evaluated for 

trueness relative to the NIST value, within-laboratory precision, and concordance within the 

participant community. NIST provides the participants with a technical summary report concerning 

their performance for each exercise and suggestions for methods development and refinement. 

Participants who have concerns regarding their laboratory’s performance are encouraged to consult 

with the MMQAP coordinators. 

All MMQAP interlaboratory studies consist of individual units of batch-prepared samples that are 

distributed to each participant. For historical reasons these studies are referred to as “Round 

Robins”. The MMQAP program and the nature of its studies are described elsewhere. [1,2] 

Round Robin XXX: Fat-Soluble Vitamins and Carotenoids in Human Serum 

Participants in the MMQAP Fat-Soluble Vitamins and Carotenoids in Human Serum Round Robin 

XXX comparability study (hereafter referred to as RR30) received four lyophilized human serum 

test samples for analysis. Unless multiple vials were previously requested, participants received one 

vial of each serum. These sera were shipped on dry ice to participants in January 1994. The 

communication materials included in the sample shipment are provided in Appendix A. 

Participants are requested to report values for all fat-soluble vitamin-related analytes that are of 

interest to their organizations. Not all participants report values for the target analytes, and some 

participants report values for non-target analytes. 

The final report delivered to every participant in RR30 has three sections: 

•	 A cover letter and a “Lies, Damned Lies, and Statistics” summary report that describes the 

samples and our analysis of the participants’ results. This cover letter and summary report 

are reproduced as Appendix B. 

•	 The “All-Lab Report” that lists all of the reported measurement results and a number of 

consensus statistics for analytes reported by more than one participant. This report also 

provides a numerical “score card” for each participant’s measurement comparability for the 

more commonly reported analytes. This report is reproduced as Appendix C. 

•	 An “Individualized Report” that graphically analyzes each participant’s results for selected 

analytes. An example “Individualized Report” is reproduced as Appendix D. 

1
 
 

 

 

 

 

 

 

 

 

 

 

Round Robin XXXI: Fat-Soluble Vitamins and Carotenoids in Human Serum 

Participants in the MMQAP Fat-Soluble Vitamins and Carotenoids in Human Serum Round Robin 

XXXI comparability study (hereafter referred to as RR31) received four lyophilized human serum 

test samples for analysis. Unless multiple vials were previously requested, participants received one 

vial of each material. These sample materials were shipped on dry ice to participants in April 1994. 

The communication materials included in the sample shipment are provided in Appendix E. 

Participants are requested to report values for all fat-soluble vitamin-related analytes that are of 

interest to their organizations. Not all participants report values for the target analytes, and some 

participants report values for non-target analytes. 

The final report delivered to every participant in RR31 has three sections: 

•	 A cover letter and a “Lies, Damned Lies, and Statistics” summary report that describes the 

samples and our analysis of the participants’ results. This cover letter and summary report 

are reproduced as Appendix F. 

•	 The “All-Lab Report” that lists all of the reported measurement results and a number of 

consensus statistics for analytes reported by more than one participant. This report also 

provides a numerical “score card” for each participant’s measurement comparability for the 

more commonly reported analytes. This report is reproduced as Appendix G. 

•	 An “Individualized Report” that graphically analyzes each participant’s results for selected 

analytes. An example “Individualized Report” is reproduced as Appendix H. 

Round Robin XXXII: Fat-Soluble Vitamins and Carotenoids in Human Serum 

Participants in the MMQAP Fat-Soluble Vitamins and Carotenoids in Human Serum Round Robin 

XXXII comparability study (hereafter referred to as RR32) received four lyophilized human serum 

test samples for analysis. Unless multiple vials were previously requested, participants received one 

vial of each material. These sample materials were shipped on dry ice to participants in July 1994. 

The communication materials included in the sample shipment are provided in Appendix I. 

Participants are requested to report values for all fat-soluble vitamin-related analytes that are of 

interest to their organizations. Not all participants report values for the target analytes, and some 

participants report values for non-target analytes. 

A preliminary report for RR32 was mailed to all participants shortly before the Micronutrients QA 

Workshop held on October 15, 1994. Based upon feedback from the Workshop participants, the 

format of the “All-Lab Report” section of the Final report was considerably modified. The revised 

final report delivered to every participant in RR32 has three sections: 

•	 A cover letter, a “Lies, Damned Lies, and Statistics” summary report that describes the 

samples and our analysis of the participants’ results, and a listing of summary statistics for 

Total Retinol, α-Tocopherol and Total β-Carotene in all sera that had been distributed more 

2
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

than once from RR01 through RR32. This cover letter and associated reports are reproduced 

as Appendix J. 

•	 The “All-Lab Report” that lists all of the reported measurement results and a number of 

consensus statistics for analytes reported by more than one participant. This report also 

provides a numerical “score card” for each participant’s measurement comparability for the 

more commonly reported analytes. This report is reproduced as Appendix K. 

•	 An “Individualized Report” that graphically analyzes each participant’s results for selected 

analytes. An example “Individualized Report” is reproduced as Appendix L. 

Round Robin 5: Vitamin C in Human Serum 

Participants in the MMQAP Vitamin C in Human Serum Round Robin 5 comparability study 

(hereafter referred to as RR05) received four frozen serum test samples, two ampoules of each of 

two different materials. These samples were shipped on dry ice to participants in January 1994. The 

available communication materials included in the sample shipment are provided in Appendix M. 

The test materials were prepared by adding equal volumes of 10 % metaphosphoric acid (MPA) to 

human serum that had been spiked with ascorbic acid. Participants were asked to provide two 

results for each vial. 

The final report delivered to all participants in RR05 consists of a cover letter and a series of Tables 

and Figures that summarize the results of the study. This report is reproduced as Appendix N. 

While not distributed to the participants in RR05, Appendix O is a revised “All-Lab Report” that 

lists the results for the test materials transformed into units of μmol/mL sample. 

No “Individualized Report” was provided to the participants in RR05. 

Round Robin 6: Vitamin C in Human Serum 

Participants in the MMQAP Vitamin C in Human Serum Round Robin 6 comparability study 

(hereafter referred to as RR06) received four frozen serum test samples and four frozen serum 

bottles of control materials for analysis. Both the test and control materials consisted of two 

containers each of two different materials. These materials were shipped on dry ice to participants in 

August 1994. The communication materials included in the sample shipment are provided in 

Appendix P. 

The test and control materials were prepared by adding equal volumes of 10 % metaphosphoric acid 

(MPA) to human serum that had been spiked with ascorbic acid. Participants were asked to analyze 

the control materials and evaluate their results before analyzing the test materials, but were not asked 

to report the values that they obtained for the control materials. Participants were asked to provide 

two results for each vial of the test samples. 

As described in NISTIR 7880-29, the data and results for RR06 were reported August 1995 in 

combination with the data and results for RR07. While not distributed to the participants in RR06, 

3
 
Appendix Q is a modified “All-Lab Report” that lists the results for the test materials transformed 

into units of μmol/mL sample. 

No “Individualized Report” was provided to the participants in RR06. 

References 

1 Duewer DL, Brown Thomas J, Kline MC, MacCrehan WA, Schaffer R, Sharpless KE, May WE, 

Crowell JA. NIST/NCI Micronutrients Measurement Quality Assurance Program: Measurement 

Repeatabilities and Reproducibilities for Fat-Soluble Vitamin-Related Compounds in Human 

Sera. Anal Chem 1994;69(7):1406-1413. 

2 Margolis SA, Duewer DL. Measurement Of Ascorbic Acid in Human Plasma and Serum: 

Stability, Intralaboratory Repeatability, and Interlaboratory Reproducibility. Clin Chem 

1994;42(8):1257-1262. 

4
 
Appendix A. Shipping Package Inserts for RR30 

The following two items were included in each package shipped to an RR30 participant: 

• Cover letter 

• Datasheet 

The cover letter and datasheet were enclosed in a sealed waterproof bag along with the samples 

themselves. 

A1
 
A2
 
ROUND ROBIN XXX RESULTS FROM LABORATORY # _________ 

DATE OF ANALYSIS ___________ 

RESULTS IN ug/mL 

SAMPLE NUMBER ANALYTE RESULT 

SERUM 191 RETINOL _____________ 

ALPHA-TOCOPHEROL _____________ 

VIAL # ___ BETA-CAROTENE _____________ 

SERUM 192 RETINOL _____________ 

ALPHA-TOCOPHEROL _____________ 

VIAL # ___ BETA-CAROTENE _____________ 

SERUM 193 RETINOL _____________ 

ALPHA-TOCOPHEROL _____________ 

VIAL # ___ BETA-CAROTENE _____________ 

SERUM 194 RETINOL _____________ 

ALPHA-TOCOPHEROL _____________ 

VIAL # ___ BETA-CAROTENE _____________ 

SERUM RETINOL _____________ 

ALPHA-TOCOPHEROL _____________ 

VIAL # ___ BETA-CAROTENE _____________ 

OPTIONAL ANALYTES: SUPPLY ONE RESULT IF AVAILABLE 

SERUM # 191 192 193 194 

TRANS-BETA CAROTENE 

ALPHA-CAROTENE 

RETINYL PALMITATE 

GAMMA-TOCOPHEROL 

LYCOPENE (TOTAL) 

9-CIS-BETA CAROTENE 

13-CIS-BETA-CAROTENE 

LUTEIN 

ZEAXANTHIN 

BETA-CRYPTOXANTHIN 

DIRECTIONS: Reconstitute with 1 mL distilled water. 

RESULTS DUE BY: March 19, 1994 

FAX RESULTS TO 301/926-8671 

A3 
Appendix B. Final Report for RR30

The following five pages are the final report for RR30 as provided to all participants: 

•	 Cover letter 

•	 A discussion entitled “Lies, Damn Lies, and Statistics” that: 

o	 describes the nature of the test samples and details any previous distributions 

o	 summarizes aspects of the study that we believe may be of interest to the 

participants 

B1 
B

2
B

3
-- . 

"Lies, Damned Lies, and Statistics" 

Mark Twain 

Brace yourselves, the attached Round Robin XXX Report differs from its predecessors. 

The most obvious changes are in the format of the "All Lab" data list and the major analyte 

summary charts for each laboratory. We've added an individualized listing of your 

submitted data and three new summaries: a rank-ordering of all laboratories based on 

similarity to the consensus values, individualized scatterplots of your data against the 

consensus values, and an individualized "precision and accuracy" breakdown. Less 

obviously, we've made major philosophical changes to our statistical analysis. 

Earlier Reports used "core groups" of experienced laboratories to define the consensus 

inter-laboratory average and standard deviation values. In statistical jargon, this is 

"trimming" or "censoring" the data. While a routine and accepted practice, effective 

trimming requires considerable time and agony on the part of the data analyst - decisions 

are always subjective and somewhat arbitrary. After study of all previous Round Robin 

data, we find that robust percentile statistics give easy-to-automate results which are in 

excellent agreement with the past trimmed values (see overleaf). 

This change is less scary than it sounds. Our new "best value" statistic - the median (the 

value for which 50% of the data are larger, 50% smaller) - is doubtless familiar to you. It 

has the wonderful property of ignoring weird values, as long as there is a good fistful of 

data with about equal numbers of high and low values. In the ideal case, where all data 

define a nice symmetric distribution, the average and the median give the same value. 

Our new "inter-laboratory variation" statistic - the interquartile range or IQR (the span of 

the central 50% of the data) - may not be as familiar, but it is a well established measure of 

dispersion. Like the median, the IQR is resistant to a few weird values. For an ideal 

normal distribution, 0.741(1QR) is equal to the standard deviation. We're also in the 

process of rethinking how to compare variation over analytes, concentration ranges, and 

time. We will discuss this in the Round Robin XXXI report. 

The take-home message for now is that our philosophical changes give the same practical 

results. Of course, our NIST results continue to provide you with independent assessments 

of the analyte concentrations. With the exceptions of the minor analytes ex-Carotene and ~­

Cryptoxanthin, NIST results continue in good accord with the inter-laboratory consensus 

values. 

B4
 
--

1 

.-.. 

~ 

~ OJ.) 

::::t ...._, 

(!) 

OJ.) 

ci::s 

i... 

(!) 

> 

< 

e 

0 

u 

"'C 

(!) 10 .§ 

~ 

Inter-laboratory Median versus Trimmed Core Average 

for Major Analytes of Round Robin XXI - XXIX 

Retinol Total ~-Carotene 

1 

Average Difference = 0.1 % 0.1 Average Difference= 0.0% 

1 0.1 1 

a-Tocoperol y-Tocoperol 

1 

Average Difference= 0.2% Average Difference= -0.4% 

10 1 

Interlaboratory Median (μg/mL) 

The parallel lines in each graphical segment show ±5% difference from equality, where the 

m difti · d fi d 100 (Trimmed Core Average - median) 

70 erence 1s e me as: median · 

There is excellent agreement between the old and the new consensus "best-value" statistics 

for the past three years (Round Robin XXI to XXIX), with no apparent systematic offsets. 

Even the extreme differences (smallest negative, largest positive) are modest: 

Retinol (-4.6%, 4.4%); cx-Tocopherol (-1.8%, 3.0%), y-Tocopherol (-8.1%,4.7%), and total 

~-Carotene (-6.3%, 6.9% ). 

B5
 
--

This Round Robin X:XX Report includes the following: 

• The "All Laboratory Data Report" 

Table 1: "Major" Analytes (2 pages) and Table 2: "Minor" Analytes (2 pages). 

Each laboratory's data on a single line, the uncensored mean and standard 

deviation, and the percentile-based consensus values. (Ok, so a-Carotene isn't a 

"major" analyte by concentration, number of reporting laboratories, or known importance ... It's in 

Table 1 to save paper ... ) 

Table 3: Analytes Reported By Only One Laboratory (1 page) 

Information values for all analytes reported by only one laboratory. The legend 

for Tables 1 and 2 is also presented on this page. 

• Relative Performance and Experience Factors (1 page): 

Table 4: Relative Laboratory Rankings 

The consensus statistics come from the central 50% of the data. This presents one 

way of telling whether you are part of the data-defined center! 

Table 5: Experience Factors Estimated by Number of Round Robin Participations. 

We also try to evaluate whether performance is related to the number of Round 

Robin participations. We believe it does, particularly when analyzing all three 

major analytes. 

• Your Laboratory's "Individualized Report" (6 pages). 

Pg. 1: Your data and the consensus values. 

Pg. 2-4: Graphical summaries of your past 3 years' performance, as measured by the 

percent difference from the median for the major analytes: Retinol, a.- and yTocopherol, and Total- and all-trans-~-Carotene. 

Pg. 5: Graphical summary of your past 3 years' performance, as measured by the 

scatterplot of your data vs. the consensus values for the major analytes. 

Pg. 6: Tabular summary of your inter-laboratory comparison "accuracy" and 

"precision" for your past 3 years' performance. 

We would appreciate hearing from you about the report: the new formats, the new 

summaries, and the statistical changes. Corrections, additions, deletions, strokes, and 

screams-of-rage are all solicited. Please let us know if any of our recorded data doesn't 

accurately reflect your real measurements! 

DaveDuewer 

Research Chemometrician 

301-975-3935 

DLDuewer@enh.NIST.gov 

~~ff~ 

Margaret Kline 

Research Biologist 

B6
 
 

 

Appendix C. “All-Lab Report” for RR30 

The following 6 pages are the “All-Lab” and the associated “Relative Performance and 

Experience Factors” reports for RR30 as provided to all participants, with three 

exceptions: 

•	 the participant identifiers (Lab) have been altered. 

•	 the order in which the participant results are listed has been altered. 

•	 the robust coefficient of variation has been recalculated using a more efficient 

robust estimator of the standard deviation: the adjusted median absolute deviation 

from the median (MADe) rather than the adjusted interquartile range (IQR). 

The data summary in the “All-Lab Report” has been altered to ensure confidentiality of 

identification codes assigned to laboratories. The only attributed results are those 

reported by NIST. The NIST results are not used in the assessment of the consensus 

summary results of the study. 

C1
 
All Laboratory Data Report for Round Robin XXX

Table 1: "Major" Analytes (micrograms/milliliter)

Total Retinol α-Tocopherol γ/β-Tocopherol Total β-Carotene trans-β-Carotene 

C2

Lab 191 192 193 194 191 192 193 194 191 192 193 194 191 192 193 194 191 192 193 1

FSV-BA 7.60 1.16 1.09 0.447 26.5 7.21 26.6 7.30 3.57 2.25 5.53 2.87 1.66 0.619 0.393 0.073 1.54 0.566 0.344 0

FSV-BD 8.15 1.22 1.13 0.446 21.4 6.60 25.4 7.20 

FSV-BE 2.26 1.06 0.97 0.399 22.1 7.40 26.8 7.50 3.49 2.55 6.05 3.27 1.92 0.712 0.454 0.069 

FSV-BF 7.14 1.15 1.06 0.460 24.0 8.00 26.4 7.30 3.50 2.60 6.60 3.10 1.67 0.661 0.440 0.076 

FSV-BH 6.51 1.01 0.89 0.432 24.0 7.50 28.0 7.59 2.78 1.98 5.06 2.54 1.59 0.579 0.369 0.048 1.50 0.553 0.345 0

FSV-BI 6.84 1.26 1.09 0.409 27.2 7.38 27.1 7.46 3.77 2.54 6.60 3.25 1.56 0.590 0.375 0.059 

FSV-BJ 6.67 1.31 1.11 0.439 22.7 6.99 25.1 7.45 3.68 2.57 6.36 3.40 1.72 0.653 0.423 0.075 

FSV-BK 6.63 1.05 0.99 0.427 26.5 6.91 26.6 6.81 

FSV-BL 10.20 1.31 1.10 0.520 21.7 7.74 30.0 8.10 

FSV-BM 7.90 0.98 0.62 0.415 26.2 7.60 30.0 7.80 

FSV-BN 5.43 0.95 0.92 24.7 8.51 28.2 3.64 2.43 5.53 2.92 1.32 0.434 0.330 0.057 1.27 0.317 0

FSV-BO 4.36 1.31 1.12 0.433 22.1 7.14 28.3 7.24 1.93 0.654 0.392 0.065 

FSV-BP 6.34 1.06 0.99 0.430 22.4 8.65 29.7 8.50 2.20 0.690 0.468 0.158 

FSV-BQ 5.41 1.05 1.01 0.418 22.7 6.40 21.2 6.60 1.47 0.642 0.448 0.078 

FSV-BR 7.09 1.08 1.07 0.434 

FSV-BS >1.04 >0.381 >0.273 >0.141 1.04 0.381 0.273 0

FSV-BT 6.27 1.04 0.93 0.390 23.6 6.74 24.3 6.61 3.59 2.32 5.78 2.88 1.57 0.569 0.361 0.050 1.47 0.534 0.328 0

FSV-BX 8.87 1.40 1.28 0.492 29.8 8.69 34.2 8.52 3.85 2.49 6.72 3.26 

FSV-BY 7.31 1.08 0.86 0.413 24.0 7.28 27.8 7.29 3.66 2.43 6.49 3.01 1.85 0.660 0.334 0.049 

FSV-BZ 26.3 8.30 29.5 6.10 3.33 2.27 5.71 2.30 1.78 0.510 0.280 0.120 

FSV-CA 6.82 1.19 1.03 0.466 25.9 6.79 30.5 6.59 

FSV-CB 6.95 1.19 1.18 0.510 24.2 7.94 28.6 7.76 >1.40 >0.600 >0.190 >0.040 1.40 0.600 0.190 0

FSV-CG 15.04 2.59 2.41 1.095 8.2 5.80 14.7 7.22 8.23 5.80 14.70 7.22 3.00 1.104 0.712 0.108 

FSV-CH 6.58 0.95 0.94 0.366 22.6 6.02 23.9 5.81 2.74 1.67 4.41 2.13 1.23 0.439 0.284 0.036 

FSV-CJ 6.45 1.05 1.08 0.436 22.8 6.88 26.4 7.45 1.33 0.487 0.344 0.053 

FSV-CK 7.13 1.27 1.16 0.425 20.9 7.18 27.7 7.17 3.46 2.62 6.57 3.29 1.91 0.676 0.396 0.062 

FSV-CL 7.57 1.30 1.32 0.580 27.7 8.93 34.9 8.01 4.32 3.01 8.25 3.60 1.51 0.590 0.410 0.100 

FSV-CM 27.3 9.07 36.3 8.59 

FSV-CO 6.83 1.04 1.06 0.403 23.7 6.97 26.9 6.85 1.71 0.601 0.400 0.069 1.65 0.553 0.354 0

FSV-CP 5.22 0.88 0.82 0.325 14.6 4.33 17.5 5.33 1.19 0.459 0.276 0.036 

FSV-CQ 6.86 1.06 1.02 0.420 26.6 7.36 28.0 7.48 1.62 0.750 1.040 nq 

FSV-CR 6.42 1.10 1.05 0.475 23.2 7.23 27.1 7.39 

FSV-CT 9.30 1.43 0.82 0.472 42.8 8.41 41.7 9.64 1.76 0.620 0.452 0.060 1.39 0.468 0.305 

FSV-CU 6.71 1.04 1.01 0.405 24.7 6.80 23.5 6.16 1.90 0.669 0.428 0.112 1.62 0.612 0.367 0

FSV-CV 7.23 1.21 1.06 0.460 25.0 7.80 27.7 7.65 3.44 2.53 6.40 3.14 1.69 0.600 0.410 0.045 

FSV-CX 6.54 0.96 0.95 0.400 21.4 6.90 25.0 7.12 3.36 2.36 5.90 3.18 1.27 0.380 0.220 0.030 

FSV-CY 1.00 1.01 0.410 24.0 6.95 27.3 7.10 1.66 0.650 0.380 <0.08 

FSV-DJ 1.16 0.97 0.460 7.80 29.4 7.90 

FSV-DL 4.51 0.77 0.69 0.379 14.8 4.64 17.6 5.98 3.20 2.56 6.27 4.26 1.54 0.606 0.364 0.057 

FSV-DM 7.35 1.16 1.08 0.433 21.5 5.60 22.6 5.46 1.67 0.558 0.357 0.047 

FSV-DS 5.17 1.05 0.74 0.390 20.3 7.73 23.2 7.64 1.49 0.642 0.235 0.060 

4/20/94 
All Laboratory Data Report for Round Robin XXX

Table 1: "Major" Analytes (micrograms/milliliter)

Total Retinol α-Tocopherol γ/β-Tocopherol Total β-Carotene trans-β-Carotene 

Lab 191 192 193 194 191 192 193 194 191 192 193 194 191 192 193 194 191 192 193 1

FSV-DX 8.18 1.11 1.00 0.422 22.4 7.41 26.9 8.73 1.28 0.463 0.296 0.043 0.02 0.016 0.012 0

FSV-EA 8.53 1.17 1.06 0.430 26.0 7.40 27.2 7.00 4.30 3.00 7.10 3.60 1.59 0.570 0.370 0.570 

FSV-EC 8.41 1.29 1.00 0.429 24.1 7.15 25.5 6.97 1.21 0.438 0.257 0.047 

FSV-EK 7.92 1.28 1.18 0.488 27.2 7.85 30.6 7.60 4.10 2.67 7.38 3.50 1.14 0.466 0.312 nq 

FSV-EX 5.86 0.94 0.86 0.370 24.1 7.28 28.5 7.43 1.76 0.610 0.400 0.050 

FSV-FF 1.27 1.08 0.434 1.65 0.573 0.362 0.081 

n 41 44 44 43 43 44 44 43 20 20 20 20 35 35 35 32 10 9 10 

Min 2.26 0.77 0.62 0.325 8.2 4.33 14.7 5.33 2.74 1.67 4.41 2.13 1.14 0.380 0.220 0.030 0.02 0.016 0.012 0

Mean 7.04 1.16 1.04 0.449 23.8 7.26 27.1 7.29 3.80 2.63 6.67 3.34 1.64 0.598 0.393 0.083 1.29 0.476 0.284 0

Max 15.04 2.59 2.41 1.095 42.8 9.07 41.7 9.64 8.23 5.80 14.70 7.22 3.00 1.104 1.040 0.570 1.65 0.612 0.367 0

SD 1.90 0.26 0.25 0.110 4.8 0.98 4.7 0.86 1.12 0.80 2.06 1.03 0.34 0.126 0.142 0.093 0.48 0.186 0.108 0

CV 27 23 24 25 20 13 17 12 29 30 31 31 21 21 36 113 37 39 38 

NIST1
 

NIST3
 

6.99 1.12 0.93 0.443 

6.62 1.00 0.88 0.411 

22.0 6.88 26.0 7.26 

22.7 6.89 27.3 7.14 

2.89 2.05 5.78 2.57 

3.34 2.34 6.14 3.09 

1.62 0.550 0.367 0.054 

1.67 0.612 0.404 0.058 

1.59 0.501 0.345 0

1.55 0.557 0.351 0

C3

Median 6.84 1.10 1.03 0.430 24.0 7.28 27.1 7.30 3.58 2.54 6.38 3.22 1.65 0.601 0.375 0.060 1.44 0.553 0.323 0

eCV 12 13 10 9 12 10 10 7 8 7 13 13 13 13 18 33 14 13 12 

4/20/94 
C4

All Laboratory Data Report for Round Robin XXX

Table 2: "Minor" Analytes (micrograms/milliliter)

Total Lycopene Total β-Cryptoxanthin Total Lutein Total Zeaxanthin Total Lutein&Zeaxanth

Lab
 191 192 193 194 191 192 193 194 191 192 193 194 191 192 193 194 191 192 193 1

FSV-BA 0.051 0.067 0.056 0.062 

FSV-BD

FSV-BE

FSV-BF 0.274 0.81 0.81 0.65 

FSV-BH 0.134 0.51 0.41 0.43 0.052 0.072 0.062 0.057 0.047 0.072 0.046 0.056 nq 0.036 nq nq 0.108 

FSV-BI 0.152 0.57 0.45 0.50 0.049 0.056 0.048 0.050 0.024 0.064 0.050 0.065 0.011 0.035 0.030 0.035 0.035 0.099 0.080 0.

FSV-BJ 0.229 0.87 0.67 0.79 

FSV-BK

FSV-BL

FSV-BM

FSV-BN 0.129 0.36 0.26 0.035 0.041 0.041 0.035 0.011 0.033 0.029 0.036 0.005 0.017 0.011 0.018 0.016 0.050 0.040 0.

FSV-BO 0.208 0.50 0.43 0.41 0.050 0.063 0.052 0.052 0.048 0.128 0.101 0.130 

FSV-BP 0.287 0.72 0.62 0.61 0.030 0.069 0.035 0.028 

FSV-BQ

FSV-BR

FSV-BS

FSV-BT 0.117 0.44 0.34 0.34 0.045 0.055 0.045 0.043 0.023 0.082 0.058 0.079 0.007 0.028 0.023 0.029 0.030 0.110 0.081 0.

FSV-BX

FSV-BY 0.167 0.62 0.51 0.48 0.056 0.075 0.056 0.057 0.023 0.074 0.053 0.063 0.010 0.039 0.030 0.033 0.035 0.114 0.095 0

FSV-BZ 0.690 0.84 0.75 0.68 0.104 0.104 0.120 0.100 

FSV-CA

FSV-CB 0.150 0.65 0.27 0.28 0.030 0.040 0.030 0.030 0.100 0.190 0.210 0

FSV-CG 0.186 0.71 0.59 0.59 0.121 0.170 0.141 0.142 

FSV-CH 0.103 0.39 0.31 0.32
 

FSV-CJ
 0.155 0.54 0.47 0.47 0.043 0.070 0.054 0.056 0.040 0.124 0.104 0

FSV-CK 0.193 0.71 0.55 0.63 0.035 0.476 0.048 0.122 0.045 0.128 0.105 0

FSV-CL
 0.150 0.63 0.54 0.54 0.070 0.090 0.070 0.060 0.070 0.160 0.150 0.120 

FSV-CM

FSV-CO 0.144 0.48 0.39 0.39 0.052 0.088 0.058 0.061 0.035 0.106 0.099 0.106 0.020 0.107 0.087 0.081 0.055 0.213 0.186 0.

FSV-CP 0.164 0.59 0.51 0.47 0.041 0.048 0.041 0.040 0.057 0.110 0.092 0

FSV-CQ

FSV-CR

FSV-CT 0.031 0.088 0.060 0.076 0.018 0.051 0.043 0.046 0.049 0.139 0.103 0.

FSV-CU 

FSV-CV 0.265 0.78 0.66 0.58 

FSV-CX 0.170 0.62 0.48 0.51 0.050 0.050 0.030 0.030 0.040 0.110 0.070 0.100 

FSV-CY

FSV-DJ

FSV-DL 0.095 0.32 0.29 0.39 0.055 0.083 0.061 0.057 

FSV-DM

FSV-DS 

4/20/94 
All Laboratory Data Report for Round Robin XXX

Table 2: "Minor" Analytes (micrograms/milliliter)

Total Lycopene Total β-Cryptoxanthin Total Lutein Total Zeaxanthin Total Lutein&Zeaxanth

Lab 191 192 193 194 191 192 193 194 191 192 193 1

FSV-DX 0.207 0.72 0.62 0.65 

FSV-EA 0.170 0.55 0.46 0.48 

FSV-EC

FSV-EK nq 0.60 0.50 0.51 

FSV-EX

FSV-FF

191 192 193 194 

0.050 0.059 0.059 0.055 

191 192 193 194 

0.029 0.083 0.075 0.083 

0.052 0.201 0.173 0.191 

nq 0.153 0.129 0.146 

n 23 24 24 23 18 18 18 18 13 14 14 14 6 7 6 6 10 11 10 

Min 0.095 0.32 0.26 0.28 0.030 0.040 0.030 0.028 0.011 0.033 0.029 0.036 0.005 0.017 0.011 0.018 0.016 0.050 0.040 0

Mean 0.197 0.61 0.50 0.51 0.051 0.093 0.055 0.058 0.041 0.104 0.087 0.097 0.012 0.045 0.037 0.040 0.046 0.126 0.110 0

Max 0.690 0.87 0.81 0.79 0.121 0.476 0.141 0.142 0.104 0.201 0.173 0.191 0.020 0.107 0.087 0.081 0.100 0.213 0.210 0

SD 0.119 0.15 0.15 0.13 0.020 0.100 0.024 0.030 0.024 0.044 0.043 0.041 0.006 0.029 0.026 0.022 0.023 0.044 0.051 0

CV 60 25 30 25 40 107 44 51 59 42 50 42 51 66 71 54 49 35 46 

NIST1

NIST3 0.204 0.63 0.55 0.53 0.036 0.051 0.041 0.041 0.032 0.099 0.077 0.082 0.011 0.039 0.034 0.030 0.043 0.138 0.111 0.

Median 0.167 0.61 0.49 0.50 0.050 0.068 0.053 0.056 0.035 0.096 0.073 0.092 0.011 0.036 0.030 0.034 0.042 0.114 0.099 0

eCV 29 26 30 27 16 31 22 16 51 36 54 45 64 33 49 37 35 18 18 

C5

4/20/94 
All Laboratory Data Report for Round Robin XXX
 

Table 3: Analytes Reported By Only One laboratory
 All concentrations in micrograms/milliliter

Analyte Code 191 192 193 194 

δ-Tocopherol NISTb 0.22 0.14 0.47 0.13 

9-&13-cis-β-Carotene FSV-BT 0.03 0.09 0.08 0.10 

trans-α-Carotene NISTb 0.025 0.021 0.018 0.015 

dihydro-Lycopene FSV-BT 0.033 0.086 0.083 0.095 

Legend for Tables 1 and 2 

nq Not quantitatively determined (i.e., reported as '0', 'trace', 'not determined', etc.) 

<x Concentration at or below "limit of quantification" x. 

Statistics (NIST's values are excluded from all calculations) 

n Number of laboratories reporting quantitative values for this analyte for this serum.
 

Min Minimum reported value.
 

Mean Average over all reported values.
 

Max Maximum reported value. 

SD Standard deviation over all values. 

CV Coefficient of Variation (% relative standard deviation): for (non-NIST) results: 100*SD/Mean 

Median Median over all reported values (i.e., 50% of values are larger, 50% are smaller.) 

eCV Estimated CV, based on the adjusted median absolute deviation from the median (MADe). 

The original report estimated eCV from the interquartile range (IQR). 

C6
 

 4/20/94 RR30_Datasummary, Page 5 / 5 
Relative Performance and Experience Factors

Table 4 

Relative Laboratory Rankings 

Lab N Ret aToc bCar 

FSV-BA 21 24 17 3 

FSV-BD 26 55 55 

FSV-BE 24 69 24 76 

FSV-BF 26 5 29 45 

FSV-BH 20 52 14 12 

FSV-BI 26 38 31 0 

FSV-BJ 12 60 21 30 

FSV-BK 11 12 40 

FSV-BL 13 88 67 

FSV-BM 10 76 60 

FSV-BN 8 81 52 64 

FSV-BO 6 74 26 48 

FSV-BP 8 14 79 94 

FSV-BQ 3 40 71 42 

FSV-BR 3 0 

FSV-BS 5 92 

FSV-BT 4 67 45 15 

FSV-BX 7 93 93 

FSV-BY 26 43 2 58 

FSV-BZ 19 74 67 

FSV-CA 25 10 69 

FSV-CB 7 62 43 

FSV-CG 10 100 83 97 

FSV-CH 11 79 76 85 

FSV-CJ 26 26 19 39 

FSV-CK 11 45 38 61 

FSV-CL 1 83 88 27 

FSV-CM 15 95 

FSV-CO 24 33 7 9 

FSV-CP 8 95 100 91 

FSV-CQ 13 2 36 82 

FSV-CR 3 31 0 

FSV-CT 7 90 98 36 

FSV-CU 8 36 62 70 

FSV-CV 12 57 33 33 

FSV-CX 3 64 50 100 

FSV-CY 17 48 5 18 

FSV-DJ 3 17 57 

FSV-DL 10 98 90 6 

FSV-DM 9 7 81 24 

FSV-DS 6 86 64 55 

FSV-DX 3 19 48 73 

FSV-EA 5 29 10 52 

FSV-EC 6 50 12 88 

FSV-EK 3 71 86 79 

FSV-EX 3 74 19 29 

FSV-FF 3 21 21 

Overall 

0 * 

66 

16 * 

13 * 

6 * 

28 * 

75 

53 

69 

59 

44 * 

25 * 

97 

94 

19 * 

50 * 

78 

3 * 

100 

34 * 

88 

63 

41 * 

84 

9 * 

72 

31 * 

81 

47 * 

22 * 

56 

91 

38 * 

gToc Legend 

63 Lab 

N 

0 Ret 

21 aToc 

89 bCar 

11 gToc 

26 

Relative Rank 

53 

Overall 

47 

42 

16 

74 

* 

95 

95 

Laboratory code 

Number of prior Round Robin participations (any analyte) 

Relative Rank for: Retinol 

Relative Rank for: a-Tocopherol 

Relative Rank for: Total b-Carotene 

Relative Rank for: g/b-Tocopherol 

An approximate measure of "closeness" to the interlaboratory 

medians in Round Robin XXX, expressed on a scale of 0 

(closest) to 100 (least close). Each of the listed ranks 

composites individual rankings for the four sera. Labs with 

Relative Rank of 0 to 50 define the "Inner" group for a given 

analyte. Labs ranking 51 to 100 define the "Outer" group. 

An approximate measure of "overall closeness" to the 

interlaboratory medians in Round Robin XXX, based on 

averaging the Relative Ranks for Retinol, a-Tocopherol, 

total b-Carotene assays. Only labs that reported all 

three analytes in Round Robin XXX have an "Overall" rank. 

Laboratories with an Overall rank of 0 to 

Table 5 

32 Average Number of Round Robin participations 

84 

Ret 

aToc 

bCar 

Overall 

5 

37 gToc 

in the last "n" Years 

n=10 n=3 n=1 

In Out In Out In Out 

12.7 9.2 6.7 6.0 2.9 2.4 

13.1 8.7 7.2 5.9 2.8 2.5 

13.2 7.4 7.1 5.6 2.7 2.6 

14.5 5.1 7.6 4.6 2.8 2.3 

7.4 3.6 5.8 3.4 2.3 1.7 

Does Experience Count? 

58 Looking at the average number of Round Robin participations for labs with 

Relative Ranks of 0 to 50 for a given analyte (the "Inner" group) versus those 

with Relative Ranks of 51 to 100 (the "Outer" group), the "Inner" laboratories 

are consistently enriched in experience. The enrichment is more pronounced 

79 for the Overall three-analyte composite than it is for individual analytes. 

Experience seems to count more as you do more. 

68 

C7
 

 4/20/94 RR30_RelativePerform, 1/1 
Appendix D. Representative “Individualized Report” for RR30 

Each participant in RR30 received an “Individualized Report” reflecting their reported 

results. Each report included a detailed analysis of the results they reported for the 

following analytes: 

• Retinol 

• α-Tocopherol 

• γ-Tocopherol 

• Total β-Carotene 

• trans-β-Carotene 

The following six pages are the “Individualized Report” for the analytes evaluated by 

participant FSV-NIST1 (listed as FSV-NISTa in the “All Lab Report”). 

D1
 
4120/94 

Individualized Round Robin XXX Report to: NIS

Your Data, Inter-laboratory Medians, and %Differences 

Serum 191 Serum 192 Serum 193 Serum 

Analyte I You Med %A n II You Med %A n II You Med %A n II You Me

Retinol 6.99 6.85 2 40 1.12 1.11 1 43 0.93 1.03 -10 43 0.44 0.4

a-Tocopherol 21.99 23.98 -8 42 6.88 7.28 -6 43 26.02 27.06 -4 43 7.26 7.2

g-Tocopherol 2.89 3.58 -19 20 2.05 2.54 -19 20 5.78 6.38 -9 20 2.57 3.2

Total b-Carotene 1.62 1.64 -1 34 0.55 0.60 -8 34 0.37 0.37 -1 34 0.05 0.0

trans-b-Carotene 1.59 1.44 11 10 0.50 0.55 -9 9 0.35 0.32 7 10 0.05 0.0

You : Your reported values for the listed analytes (micrograms/milliliter) 

Med : The median of the values reported by all participating laboratories (excluding NlST.) 

%.A : The percent difference between your value and the median (reported for main analytes only.) 

n : The number oflaboratories reporting quantitative values for this analyte in this serum (excluding NlST.) 

Please check our recorded values against your records. 

Fax any corrections to: (301) 926-8671, c/o Donna Sirk, 222/B156, NIST, Gaithersburg, MD 20899 

.1 

D2
50 

a 

:a 25 

cu 

~ a x ..... 

"O x 

cu I :E 0 I 

~ 

8 

* 0 

0 

-

<] -25 

~ 

-50 

4120/94 

Individualized Round Robin :XXX Report to: NIS

Retinol, %Li in Round Robin XXI - XXIX 

x 

x x x 

x x x x x v 

x I x x x v I 

I I I x v 11 I 

I I v v I I- mm I 

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 I 

4 4 4 4 4 4 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 8 8 8 8 8 

4 5 6 7 8 9 0 5 6 7 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 I 2 3 4 5 

Serum 

/ 

1 1 

8 8 

6 7 

D3
50 

i:: 

= ;a 25 

Cl) 

1~ ~ a 

;a 

Cl) 

~ 0 I 

~ 

8 

* 

8 

""""' 

<:J -25 

~ 

-50 

4120/94 

Individualized Round Robin XXX Report to: NIS

Tocopherol, %Li in Round Robin XXI - XXIX 

x 

x 

I 

I 

1 1 1 1 1 1 1 

4 4 4 4 4 4 5 

4 5 6 7 8 9 0 

x 

x 

I 

I 

I 

1 1 1 1 

5 5 5 5 

5 6 7 9 

• g-Tocopherol a-Tocopherol 

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 

6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 

Serum 

1 1 1 1 1 

8 8 8 8 8 

1 2 3 4 5 

1 1 

8 8 

6 7 

D4
50 

c: 

ti:! 

:a 25 

Q) 

~ 

-

a x 

:a x 

Q) 

I ~ 0 I 

~ 

d 

* 

8 

.-I 

<] -25 

~ 

-50 _J 

4/2G.'94 

Individualized Round Robin :XXX Report to: NI

b-Carotene, %L\ in Round Robin XXI - XXIX 

x .~ x 

I ~ X I x x 

I . I i 111~ I I 

• All trans-b-Carotene 11J Total b-Carotene 

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 

4 4 4 4 4 4 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 8 8 8 8 8 8 8 

4 5 6 7 8 9 0 5 6 7 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 1 2 3 4 5 6 7 

Serum 

/ 

D5
-±20% 

- ±50% 

-±20% 

- - ±50% 

4/20/94 

Individualized Round Robin XXX Report to: NIS

Inter-laboratory Median Vs Laboratory NISTl Values 

Retinol 

a-Tocopberol,,, 

ATotal 

elltrans 

-±20% 

- - ±50% 

-±20% 

- ±50% 

/ 

b-Carotene 

, 

, 

g-Tocopherol , , ' 

L

Shaded Symbols: R

Black Symbols: 

Ordinate: Median 

Abscissa: Your re

Inter

Adequately intercomp

±20% lines. H you h

the ±50% lines, your 

not consistent with th

laboratories. H your 

higher or lower than t

may be consistent bu

H your data show inc

concentrations, your 

may not be what you 

H there are one or tw

might be calculation 

We would appreciate 

any such problems. 

D6
Individualized Round Robin :XXX Report to: NIS

(Provisional) Performance Summary 

XXI 

XXII 

xxm 

XXIV 

xxv 

XXVI 

xxvn 

xxvm 

XXIX 

xxx 

Ret a Toe gToc Total 

mA vA mA vA mA vA mA vA 

-3 4 -3 1 -10 6 12 18 

-10 4 -6 4 0 4 7 6 

-5 4 -2 4 -1 16 -5 16 

2 5 0 4 -6 8 7 10 

1 3 -1 3 2 3 -15 7 

-7 6 4 1 6 4 2 10 

-1 3 -2 1 -14 4 9 8 

-1 6 -5 3 -17 5 -5 5 

(Provisional) Performance Criteria 

trans 

mA vA 

11 14 

1 9 

-16 9 

-10 6 

7 7 

4 9 

In past Round Robins,the absolute value of the %A of 

each measurement was evaluated as follows: 

4l2Gl94 

0-5% : Exceptional 

6-10% : Acceptable 

11-20% : Marginal 

>20%: Poor 

Ret : Retinal 

aToc : a-Tocopherol 

gToc : g-Tocopherol 

Total: Total b-Carotene 

trans : All trans-b-Carotene 

Legend 

mA : Mean difference, the average %A for all sera of 

%A= lOO(Your value- median) I median 

v A : Difference variability, one standard deviation o

Rational 

There are no definitive methods for any of these fat-soluble vitam

You can't judge how well you are performing in any absolute sens

how your measurements agree with the group's consensus values - 

Just as with absolute comparisons, there are two seperate-but-kind

comparison. The first, related to accuracy, can be estimated as the 

the average %A [lOO(your value - median)/median] over all sera o

The second, related to precision, can be estimated as the "differen

one standard deviation of the %A over all sera of a given Round R

It's obviously best to be accurate and precise (small ml\, small vA

precision (small vA) with poor accuracy (large mA) is better than t

values are internally consistent and can be related to the group con

CONSTANT over time. Poor precision (large vA) suggests that y

qualitatively different from that used by NIST and the majority of 

This all assumes that the expected "%A" does not depend on analy

near or below your "limit of quantification," and may not be true e

More on this later ... 

/ 

D7
Appendix E. Shipping Package Inserts for RR31 

The following two or three items were included in each package shipped to an RR31 participant: 

•	 Cover letter 

•	 Datasheet for RR31 serum materials 

•	 Datasheet for soy oil and candidate SRM 2383: Fat-Soluble Vitamins and Carotenoids in 

Food materials. Only those participants who had previously agreed to evaluate these 

materials received this datasheet. It is included here because it is discussed in the RR31 

cover letter. 

The cover letter and datasheet(s) were enclosed in a sealed waterproof bag along with the 

samples themselves. 

E1 
E2
E

3
ROUND ROBIN XXXI RESULTS FROM LABORATORY # _________ 

DATE OF ANALYSIS ___________ 

RESULTS IN ug/mL 

SAMPLE NUMBER ANALYTE RESULT 

SERUM 195 RETINOL _____________ 

ALPHA-TOCOPHEROL _____________ 

VIAL # ___ BETA-CAROTENE _____________ 

SERUM 196 RETINOL _____________ 

ALPHA-TOCOPHEROL _____________ 

VIAL # ___ BETA-CAROTENE _____________ 

SERUM 197 RETINOL _____________ 

ALPHA-TOCOPHEROL _____________ 

VIAL # ___ BETA-CAROTENE _____________ 

SERUM 198 RETINOL _____________ 

ALPHA-TOCOPHEROL _____________ 

VIAL # ___ BETA-CAROTENE _____________ 

SERUM RETINOL _____________ 

ALPHA-TOCOPHEROL _____________ 

VIAL # ___ BETA-CAROTENE _____________ 

OPTIONAL ANALYTES: SUPPLY ONE RESULT IF AVAILABLE 

SERUM # 195 196 197 198 

TRANS-BETA CAROTENE 

ALPHA-CAROTENE 

RETINYL PALMITATE 

GAMMA-TOCOPHEROL 

LYCOPENE (TOTAL) 

9-CIS-BETA CAROTENE 

13-CIS-BETA-CAROTENE 

LUTEIN 

ZEAXANTHIN 

BETA-CRYPTOXANTHIN 

DIRECTIONS: 

RESULTS DUE BY: June 14, 1994 

FAX RESULTS TO 301/926-8671 

E4 
E5
Appendix F. Final Report for RR31

The following six pages are the final report for RR31 as provided to all participants: 

•	 Cover letter 

•	 A discussion entitled “Lies, Damn Lies, and Statistics” that: 

o	 describes the nature of the test samples and details any previous distributions 

o	 summarizes aspects of the study that we believe may be of interest to the 

participants 

F1 
 

 

 

 

 

 

U N I TE D ST A T ES D EP A R TM E N T O F C O M M ER C E 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-0001 

August 8, 1994 

Dear Colleague: 

Enclosed is the summary report of the results for Round Robin XXXI (Serum 195-198). In this 

round robin exercise, serum 195 is a 50:50 volumetric mix of serum 198 and stripped serum; 

serum 197 is a 25:75 volumetric mix. Serum 196 was previously distributed in Round Robin 

XXIX as serum 183. 

Tables 1-4 provide a summary of data for all laboratories. As for Round Robin XXX, the overall 

laboratory performance for retinol and γ- and α-tocopherol for this round robin exercise is good. 

The average estimated coefficient of variation (eCV) is about 11% for retinol 10.5% for 

α-tocopherol, and about 11 % for γ-tocopherol. The overall laboratory performance for total 

β-carotene improved somewhat from the last round robin exercise. The interlaboratory variation 

for total β-carotene in Round Robin XXX was approximately 21%; for this round robin study, 

the variation is about 16%. The higher interlaboratory variation was perhaps due to the difficulty 

of making measurements at much lower levels (≤100 ng/mL vs ≥300 ng/mL). 

The concentration of retinyl palmitate was enriched in all samples used in this exercise. The 

average eCV for retinyl palmitate was about 26%. We will continue to enrich the levels of 

retinyl palmitate in future round robin samples in an effort to better assess laboratory 

performance for this analyte. 

Data for evaluating your laboratory's performance relative to the other participants’ is provided 

in Table 5. Your laboratory's individual laboratory performance is provided in pages 1-8 of the 

attached report and includes a graphical summary of laboratory's past performance for Round 

Robins XXII-XXXI and a tabular summary of your interlaboratory accuracy and precision. 

The performance criteria that was previously established for past round robins is used to 

summarize laboratory performance for Round Robin XXXI. By convention, 0-5% bias from the 

assigned value represents EXCEPTIONAL performance, 6-10% ACCEPTABLE performance, 

11-20% MARGINAL performance and >20% POOR performance relative to the current stateof-the-practice for these measurements. 

If you have concerns regarding your performance or are a lab whose performance would be rated 

"POOR" based on the convention stated above, we suggest that you obtain a unit of SRM 968a 

and analyze all three levels. If, with minor method modifications your measured values do not 

agree with the certified values, feel free to contact us for consultation. SRM 968a can be 

obtained through the NIST Standard Reference Materials Program (301/975-6776 or FAX: 

301/948-3730) 

F2 
 

Round Robin XXXII samples were shipped during the last week of July. If you have not 

received these samples, please call Ms. Donna Sirk at 301/975-3174. Results are due by August 

30. The results from this study will be discussed at the Micronutrients QA Workshop, which 

will be held on Saturday, October 15, 1994 at the Crystal Gateway Marriot Hotel in Arlington, 

VA. 

If you have questions, please contact me at 301/975-3120. 

Sincerely, 

Jeanice Brown Thomas 

Research Chemist 

Organic Analytical Research Division 

Chemical Science and technology Laboratory 

Enclosures 

F3 
(, 

' 

c 

"Lies, Damned Lies, and Statistics" 

Mark Twain 

For better or worse, the attached Round Robin XXXI Report is not much different from 

XXX's ... Actually.just a few cosmetic refinements and two IMPORTANT pages of plots 

specific to the RR XXXI samples. 

Refinements: The "All Lab" report has been broken into five chunks: 

(1) Retinoids and Tocopherols (retinol, retinyl palmitate, a- and y-tocopherol). 

(2) Carotenes (total and trans;3-carotene, total a-carotene, total and trans-lycopene). 

(3) Xanthophylls (13-cryptoxanthin, lutein, zeaxanthin, lutein & zeaxanthin). 

We're cheating on the "lutein & zeaxanthin" data ... some of you report lutein and 

zeaxanthin separately, some report only the combined value, some report both. 

Since we've got a data column for the combined analytes, we've decided to fill it in 

as best we can by adding together all separately reported lutein and zeaxanthin 

pairs. 

(4) Analytes reported by only single laboratories. 

(5) Relative Rankings. 

This time, we've scaled the Rankings from 1 (among the 25% of reporting labs 

closest to the interlaboratory medians) to 4 (among the 25% of reporting labs 

farthest from the medians). We've also changed how we average across sera (by 

ranks rather than pooled CV), but the results don't change noticeably at 1-4 

resolution. 

Same-as-before: The "Individualized" report's first six pages are identical to those of 

Round Robin XXX (except that RRs XXII through XXX are now the reference period for 

the graphs). 

Pg. 1 Data table 

Pg. 2 %Bias barchart for retinol 

Pg. 3 %Bias barchart for a- and y- tocopherol 

Pg. 4 %Bias barchart for total and trans-P-carotene 

Pg. 5 Interlaboratory median vs. your value scatterplots for retinol, a- and y- tocopherol, 

total and trans-j3-carotene 

Pg. 6 (Provisional) Performance Summary 

New & IMPORTANT 

The "Individualized" report's pages 7 and 8 present information that may help you assess 

your absolute measurement performance. Serum 196 was a replicate of serum 183 (from 

RR XXIX). Serum 195 was a 50:50 volumetric mix of serum 198 and delipidized serum; 

serum 197 was a 25:75 volumetric mix. Your values, the central 50% of the interlaboratory 

results, and the expected relationships among the sera are displayed for all analytes for 

which at least five laboratories reported values. The displays are as follows: 

F4
 
c 

c 

l 

Expected 

equality 

Your 

value 

Oct-93 Jun-94 

Replicates • • 

• Central 50% 

~ -----(3rdQ, Median, lstQ) 

\ interlaboratory values 

' ' $ 

• - Expected linear ·~-~- ', relationship 

~ ' ' ' 

I.Ox O.Sx 0.25x 

• 0·1 . • 1 utions 

How should you interpret these little graphs, and why should you care? If you analyze for 

one or more of the above analytes, the left-hand side of each graph lets you quickly spot 

how stable your assay has been over the last year. If the black dots aren't pretty near each 

other, your assay is not stable. 

The right-hand side of each graph plots the dilution series and draws the expected linear 

relation. If the black dots aren't parallel to the line, your assay is not linear (or, if the 

lowest concentration is too high, your assay was pushed past its limit of quantification.) If 

the black dots aren't in the right order (high, middle, low), you need to examine the plots 

.. for all analytes that you report Is the pattern the same for all analytes? Then you may 

have a problem in your extraction/sample prep/sample identification system. If it's just in 

one analyte, then you may need to critically examine your peak-recognition and 

quantification method. 

The central 50% boxes (showing the 3rd quartile, median, and 1st quartile values) give you 

another look at how comparable your values are with those of other laboratories. More 

importantly, the discord between the boxes for replicate sera and/or deviation from linearity 

in the dilution series highlight "analytical opportunities" with the analytes: retinyl 

palmitate, lutein, and total lycopene. 

We promised to discuss "how to compare variation over analytes, concentration ranges, and 

time" in Round Robin XXX's report. That's too big a bite for one sitting; we'll start with 

F5
 
( 

c 

the relationships between the previously reported total standard deviation (SD) and 

"Trimmed Core" standard deviation (TC-SD) and our "new" dispersion statistic: the 

~stimated .S.tandard Deviation (eSD). The eSD is defined as 0.741 times the interquartile 

range (IQR) - our old friend, the central 50% of the data. The factor 0. 741 is the number of 

"standard deviations" (z) required to span the central 50% of a normal distribution: 

1 1 1 

Z+25% - Z-25% = 0.674 + 0.674 = 1.349 = 0.74l 

Round Robin XXI - XXIX Inter-laboratory eSD versus Total and "Trimmed Core" SD 

for Retinol, Total ~-Carotene, and ex- and y-Tocopherol 

~ bO 

:1. 

= 0 

·--~ 0.1 ·-> Q) 

Q 

'E 

~ 

"O 

c:: .5 0.01 

(/) 

-~ -0 

~ 

"O 

c:: 

~ 

~ 0 

u 

"O 

s 

s 

E5 

0.01 0.1 

Retinol Total P-Carotene 

0.01 

y-Tocopherol 

0.1 

Estimated Standard Deviation (eSD), μg/mL 

o Total (all reported values) SD 

• Trimmed Core SD 

- SD=eSD 

---- SD= eSD/2 112, eSD*2 112 

0.1 

F6
 
c 

c 

c 

Unlike the location statistics (median vs. "Trimmed Core") compared in the Round Robin 

:XXX report, eSD is not exactly equal to any previously reported dispersion estimate. 

There are many plausible dispersion estimates, perhaps the largest being the SD (open 

circles) and the smallest being TC-SD. This is a consequence of the "Trimmed Core" 

selection process, which insured that the estimated dispersion would be lower for the 

subset than for the whole. 

The eSD is closely proportional to TC-SD for all four analytes for (nearly) all sera, 

although it generally is about a factor of "2 larger. Whether eSD is a tad large or the 

TC-SD values were a tad small really can't be resolved: they clearly show the same trends 

for retinol, cx-tocopherol and total ~-carotene. The relationship between eSD and TC-SD 

for y-tocopherol appears somewhat different than for the other three: this actually reflects a 

differential "trimming" process used with this "semi-major" analyte and inclusion of the 

NIST laboratories into the reported SD and TC-SD. We could cheat and redo the trimming 

and calculations to be in better accord with the other three analytes, but choose rather to 

just use the eSD and go forward. 

The Round Robin XXXII Report will discuss how to actually use the median and eSD 

statistics to monitor analytical variation. 

Once again, your comments and suggestions are welcome. If you discover any errors in 

our recording or interpretation of your data, please let us know! 

Dave Duewer 

Research Chemometrician 

301-975-3935 

DLDuewer@enh.NIST.gov 

/7ft?':'.~/ ~- Margaret Kline 

Research Biologist 

F7
 
 

 

Appendix G. “All-Lab Report” for RR31 

The following eight pages are the “All-Lab Report” for RR31 as provided to all 

participants, with three exceptions: 

•	 the participant identifiers (Lab) have been altered. 

•	 the order in which the participant results are listed has been altered. 

•	 the robust coefficient of variation has been recalculated using a more efficient 

robust estimator of the standard deviation: the adjusted median absolute deviation 

from the median (MADe) rather than the adjusted interquartile range (IQR). 

The data summary in the “All-Lab Report” has been altered to ensure confidentiality of 

identification codes assigned to laboratories. The only attributed results are those 

reported by NIST. The NIST results are not used in the assessment of the consensus 

summary results of the study. 

G1 
All Laboratory Report for Round Robin XXXI

Table 1: Retinoids and Tocopherols (micrograms/milliliter) 

Total Retinol Retinyl Palmitate α-Tocopherol γ/β-Toc

G2

Lab 195 196 197 198 195 196 197 198 195 196 197 198 195 196 

FSV-BA 0.389 0.564 0.213 0.744 0.106 0.149 0.052 0.258 6.38 11.5 3.46 13.8 1.20 1.82 

FSV-BD 0.383 0.552 0.200 0.751 6.90 11.0 3.70 12.6 

FSV-BE 0.355 0.522 0.184 0.702 7.26 11.2 3.68 13.3 1.46 2.00 

FSV-BF 0.415 0.597 0.198 0.780 7.78 12.2 3.82 15.5 1.34 1.93 

FSV-BH 0.273 0.494 0.142 0.611 8.08 12.1 4.09 15.6 1.07 1.38 

FSV-BI 0.346 0.491 0.166 0.671 0.158 0.149 0.074 0.352 7.79 12.1 3.86 14.8 1.44 1.88 

FSV-BJ 0.412 0.588 0.210 0.811 0.090 0.100 nq 0.190 7.50 10.8 3.91 13.1 1.56 1.88 

FSV-BK 0.367 0.537 0.200 0.721 6.44 10.3 3.40 12.9 

FSV-BL 0.430 0.601 0.229 0.802 9.30 14.1 4.69 16.1 

FSV-BM 0.363 0.591 0.162 0.772 8.40 12.2 4.20 15.1 

FSV-BN 0.570 0.243 14.2 

FSV-BO 0.352 0.581 0.197 0.713 6.09 11.0 3.58 12.7 

FSV-BP 0.410 0.590 0.210 0.800 7.53 11.4 4.24 15.2 

FSV-BQ 0.319 0.513 0.147 0.728 6.12 10.4 1.95 13.5 

FSV-BR 0.401 0.622 0.195 0.789 

FSV-BS

FSV-BT 0.365 0.544 0.261 0.691 0.133 0.151 0.058 0.321 6.91 10.8 3.41 13.8 1.30 1.70 

FSV-BY 0.348 0.517 0.176 0.608 0.111 0.082 0.037 0.265 7.30 10.8 3.37 13.8 1.39 1.69 

FSV-BZ 6.97 11.5 3.23 13.3 1.56 1.75 

FSV-CA 0.417 0.614 0.250 0.757 7.82 12.4 4.12 18.7 

FSV-CB 0.420 0.650 0.200 0.810 8.41 10.8 4.37 14.9 

FSV-CG 0.116 0.168 0.063 0.231 1.40 2.4 0.68 3.0 

FSV-CH 0.243 0.502 0.156 0.598 5.68 11.9 2.95 13.1 0.80 1.57 

FSV-CJ 0.390 0.525 0.226 0.745 8.07 11.2 3.76 14.9 

FSV-CK 0.318 0.493 0.186 0.682 6.59 11.0 4.26 13.6 1.35 1.80 

FSV-CO 0.375 0.545 0.192 0.736 6.36 11.6 2.68 13.7 

FSV-CP 6.45 11.0 4.72 14.2 

FSV-CQ 0.310 0.450 0.170 0.630 7.55 13.4 3.79 15.6 

FSV-CR 0.390 0.570 0.200 0.770 7.20 11.3 3.60 14.5 

FSV-CU 0.395 0.539 0.201 0.685 0.086 0.118 0.074 0.172 6.63 10.9 3.08 12.3 

FSV-CV 0.370 0.560 0.195 0.723 7.20 11.0 3.38 14.4 

FSV-CX 0.390 0.600 0.210 0.730 0.030 0.060 0.050 0.330 7.61 11.7 4.10 14.4 1.48 2.05 

All Lab Report 
All Laboratory Report for Round Robin XXXI

Table 1: Retinoids and Tocopherols (micrograms/milliliter) 

Total Retinol Retinyl Palmitate α-Tocopherol γ/β-Toc

Lab 195 196 197 198 195 196 197 198 195 196 197 198 195 196 

FSV-CY 0.383 0.533 0.195 0.694 6.46 11.5 2.75 14.6 

FSV-DJ 0.450 0.710 0.260 0.840 8.30 13.5 4.10 16.1 

FSV-DK 0.410 0.620 0.190 0.810 6.90 10.3 4.40 13.0 

FSV-DL 0.366 0.548 0.194 0.710 6.83 11.8 3.51 14.3 1.24 1.76 

FSV-DS 0.380 0.640 0.240 0.800 7.00 11.9 4.32 14.3 

FSV-DX 0.405 0.570 0.226 0.721 7.18 12.3 3.63 14.1 

FSV-EA 0.311 0.485 0.157 0.637 6.80 11.7 3.40 14.1 1.08 1.50 

FSV-EC 0.351 0.545 0.170 0.725 7.53 11.8 3.56 15.3 

FSV-EK 0.413 0.552 0.194 0.775 5.74 13.3 2.21 13.9 1.54 1.82 

FSV-EX 0.360 0.460 0.190 0.660 7.69 11.2 3.54 14.8 

G

3

n 38 38 38 39 7 7 6 8 39 39 39 40 15 15 

Min 0.116 0.168 0.063 0.231 0.030 0.060 0.037 0.172 1.40 2.4 0.68 3.0 0.80 1.38 

Mean 0.366 0.547 0.194 0.711 0.102 0.116 0.058 0.266 7.03 11.4 3.58 14.0 1.32 1.77 

Max 0.450 0.710 0.261 0.840 0.158 0.151 0.074 0.352 9.30 14.1 4.72 18.7 1.56 2.05 

SD 0.060 0.083 0.036 0.103 0.040 0.036 0.015 0.065 1.21 1.7 0.77 2.1 0.21 0.18 

CV 16 15 18 14 40 32 25 24 17 15 22 15 16 10 

NISTa 

NISTb 

NISTc 

Median 

eCV 

0.380 0.558 0.192 0.710 

0.369 0.534 0.194 0.702 

0.411 0.582 0.206 0.784 

nq 0.130 0.036 0.208 

0.085 0.141 0.037 0.251 

6.55 10.9 3.36 13.5 

7.09 11.1 3.17 13.6 

8.04 12.6 3.42 15.7 

1.25 1.75 

1.33 1.74 

1.47 1.96 

0.378 0.550 0.195 0.725 

11 11 11 10 

0.106 0.118 0.055 0.262 

28 39 31 36 

7.18 11.5 3.63 14.2 

12 7 16 7 

1.35 1.80 

14 8 

All Lab Report 
All Laboratory Report for Round Robin XXXI

Table 2: Carotenes and Lycopene (micrograms/milliliter) 

Total β-Carotene trans-β-Carotene Total α-Carotene Total Lycopene 

G

4

Lab 195 196 197 198 195 196 197 198 195 196 197 198 195 196 197 198 

FSV-BA 0.347 0.398 0.173 0.680 0.312 0.366 0.168 0.628 0.014 0.046 0.010 0.037 

FSV-BD

FSV-BE 0.366 0.390 0.144 0.749 0.007 0.027 0.004 0.015 

FSV-BF 0.536 0.289 0.249 0.784 0.043 0.055 0.010 0.072 0.077 0.307 0.015 0.211 

FSV-BH 0.340 0.352 0.160 0.678 0.312 0.325 0.146 0.626 0.016 0.040 nd 0.032 0.053 0.194 0.023 0.111
 

FSV-BI
 0.366 0.391 0.155 0.722 0.018 0.047 0.009 0.030 0.060 0.231 0.026 0.121 

FSV-BJ 0.329 0.336 0.145 0.684 0.024 0.049 0.020 0.046 0.072 0.320 0.034 0.018 

FSV-BK

FSV-BL

FSV-BM

FSV-BN 0.301 0.042 0.102 

FSV-BO 0.355 0.352 0.178 0.745 0.015 0.021 0.014 0.047 0.073 0.187 0.023 0.120 

FSV-BP 0.293 0.289 0.146 0.619 0.022 0.036 0.015 0.030 0.129 0.294 0.074 0.200 

FSV-BQ 0.330 0.360 0.130 0.630 

FSV-BR

FSV-BS 0.353 0.260 0.160 0.511 

FSV-BT 0.358 0.317 0.150 0.682 0.332 0.297 0.138 0.631 0.016 0.038 0.005 0.028 0.076 0.194 0.028 0.134 

FSV-BY 0.355 0.260 0.137 0.633 0.020 0.030 0.012 0.039 0.062 0.216 0.014 0.124 

FSV-BZ 0.380 0.400 0.194 0.588 0.034 0.040 0.032 0.040 0.030 0.020 nq 0.010 

FSV-CA

FSV-CB 0.276 0.301 0.087 0.626 0.015 0.022 0.004 0.018 0.030 0.132 0.011 0.073 

FSV-CG 0.366 0.384 0.163 0.747 

FSV-CH 0.218 0.333 0.119 0.594 0.009 0.027 0.010 0.013 0.031 0.214 0.014 0.077 

FSV-CJ 0.020 0.036 0.002 0.032 0.112 0.312 0.045 0.217 

FSV-CK 0.335 0.309 0.089 0.649 0.021 0.046 0.006 0.050 0.071 0.129 0.017 0.189 

FSV-CO 0.356 0.385 0.173 0.734 0.342 0.330 0.135 0.623 0.042 0.054 0.027 0.063 0.056 0.191 0.028 0.106 

FSV-CP 0.296 0.327 0.139 0.638 0.016 0.043 0.005 0.039 0.003 0.229 0.027 0.004 

FSV-CQ 0.242 0.277 0.073 0.516

FSV-CR

FSV-CU 0.568 0.579 0.287 0.973 0.508 0.521 0.270 0.922 

FSV-CV 0.335 0.395 0.153 0.667 0.103 0.410 0.020 0.228 

FSV-CX 0.320 0.190 0.180 0.530 0.010 0.020 <0.01 0.020 0.070 0.190 0.040 0.140 

All Lab Report 
All Laboratory Report for Round Robin XXXI

Table 2: Carotenes and Lycopene (micrograms/milliliter) 

Total β-Carotene trans-β-Carotene Total α-Carotene Total Lycopene 

Lab 195 196 197 198 

FSV-CY 0.233 0.233 0.114 0.817

FSV-DJ

FSV-DK

FSV-DL 0.281 0.320 0.124 0.671 

FSV-DS 0.393 0.452 0.250 0.753 

FSV-DX 0.240 0.345 0.092 0.712 

FSV-EA 0.330 0.345 0.150 0.596 

FSV-EC 0.346 0.376 0.160 0.680 

FSV-EK 0.287 0.347 0.189 0.625 

FSV-EX 0.340 0.350 0.150 0.680 

195 196 197 198 

0.228 0.335 0.092 0.635 

195 196 197 198 

0.019 0.043 0.010 0.045 

0.017 0.067 nd 0.030 

0.016 0.053 0.009 0.037 

195 196 197 198 

0.044 0.148 0.018 0.104 

0.061 0.306 0.024 0.178 

0.052 0.193 0.020 0.117 

0.235 0.111 

G

5

n 30 30 30 31 7 7 7 7 21 21 18 22 20 21 19 22 

Min 0.218 0.190 0.073 0.301 0.228 0.260 0.092 0.511 0.007 0.020 0.002 0.013 0.003 0.020 0.011 0.004 

Mean 0.337 0.346 0.155 0.668 0.341 0.348 0.158 0.654 0.020 0.040 0.011 0.037 0.063 0.222 0.026 0.122 

Max 0.568 0.579 0.287 0.973 0.508 0.521 0.270 0.922 0.043 0.067 0.032 0.072 0.129 0.410 0.074 0.228
 

SD 0.074 0.070 0.047 0.111 0.084 0.083 0.055 0.126 0.009 0.012 0.008 0.014 0.029 0.084 0.015 0.064
 

CV 22 20 31 17 25 24 35 19 48 31 71 39 47 38 55 52
 

NISTa 0.361 0.364 0.164 0.690 0.295 0.307 0.131 0.661
 

NISTb
 0.333 0.348 0.118 0.659 0.278 0.318 0.103 0.592 0.106 0.291 0.050 0.192 

NISTc 0.346 0.392 0.116 0.732 0.304 0.357 0.095 0.655 0.022 0.050 0.009 0.052 0.110 0.329 0.021 0.235 

Median 0.338 0.346 0.150 0.678 0.332 0.330 0.146 0.628 0.017 0.040 0.010 0.037 0.062 0.214 0.023 0.118
 

eCV
 13 16 23 12 9 15 14 1 26 33 66 30 31 19 32 39 

All Lab Report 
All Laboratory Report for Round Robin XXXI

Table 3: Xanthophylls (micrograms/milliliter) 

Total β-Cryptoxanthin Total Lutein Total Zeaxanthin Total Lu

G

6

Lab 195 196 197 198 195 196 197 198 195 196 197 198 195 

FSV-BA 0.013 0.059 0.008 0.029 0.050 0

FSV-BD

FSV-BE

FSV-BF

FSV-BH nq 0.056 nq 0.025 nq 0.047 nq 0.063 nq nq nq nq 

FSV-BI 0.014 0.057 0.007 0.023 0.024 0.045 0.013 0.045 0.009 0.020 0.005 0.015 0.033 0

FSV-BJ

FSV-BK

FSV-BL

FSV-BM

FSV-BN 0.015 

FSV-BO 0.008 0.040 nq 0.014 0.037 0

FSV-BP 0.004 0.040 0.002 0.017 

FSV-BQ

FSV-BR

FSV-BS

FSV-BT 0.014 0.050 0.008 0.030 0.027 0.052 0.020 0.055 0.013 0.024 0.009 0.019 0.064 0

FSV-BY 0.020 0.045 0.009 0.031 0.020 0.036 0.010 0.041 0.010 0.014 0.006 0.017 0.030 0

FSV-BZ 0.020 0.070 0.010 0.070 

FSV-CA

FSV-CB 0.006 0.025 0.003 0.011 0.050 0

FSV-CG

FSV-CH

FSV-CJ 0.012 0.050 0.004 0.029 0.047 0

FSV-CK 0.013 0.051 0.005 0.025 0.042 0

FSV-CO 0.034 0.083 0.013 0.036 0.182 0.073 0.028 0.097 0.072 0.039 0.017 0.042 0.254 0.

FSV-CP 0.061 0.042 0.061 0.020 0.052 0

FSV-CQ

FSV-CR

FSV-CU

FSV-CV

FSV-CX 0.010 0.030 0.010 0.020 0.020 0.080 0.010 0.050 

All Lab Report 
All Laboratory Report for Round Robin XXXI

Table 3: Xanthophylls (micrograms/milliliter) 

Total β-Cryptoxanthin Total Lutein Total Zeaxanthin Total Lu

Lab 195 196 197 198 195 196 197 198 195 196 197 198 195 

FSV-CY

FSV-DJ

FSV-DK

FSV-DL 0.020 0.099 0.006 0.312 0.021 0

FSV-DS

FSV-DX 0.024 0.033 0.012 0.048 0.023 0.029 0.011 0.032 0.047 0.

FSV-EA 0.014 0.041 0.008 0.024 

FSV-EC

FSV-EK 0.112 0.020 0.072 0.080 

FSV-EX

G

7

n 14 16 13 16 8 9 7 9 5 5 5 5 12 

Min 0.004 0.025 0.002 0.011 0.020 0.033 0.010 0.041 0.009 0.014 0.005 0.015 0.021 0

Mean 0.017 0.055 0.011 0.041 0.042 0.056 0.015 0.061 0.025 0.025 0.010 0.025 0.061 0

Max 0.061 0.112 0.061 0.312 0.182 0.080 0.028 0.097 0.072 0.039 0.017 0.042 0.254 0

SD 0.015 0.024 0.015 0.073 0.057 0.018 0.007 0.018 0.027 0.009 0.005 0.012 0.062 0

CV 84 43 138 176 134 31 47 30 105 38 50 46 102 

NISTa

NISTb 

NISTc 

Median 

eCV 

0.010 0.035 0.005 0.014 

0.009 0.041 0.004 0.018 

0.024 0.037 0.014 0.046 

0.026 0.045 0.012 0.051 

0.016 0.021 0.005 0.022 

0.007 0.020 0.004 0.013 

0.040 0.

0.033 0

0.014 0.050 0.008 0.025 

52 27 37 31 

0.022 0.052 0.012 0.055 

13 51 25 27 

0.013 0.024 0.009 0.019 

46 31 49 31 

0.047 0

24 

All Lab Report 
All Laboratory Report for Round Robin XXXI
 Table 4: Analytes Reported By Only One Laboratory 

Analytes Reported By One Laboratory 

Values in μg/mL 

Analyte Code 195 196 197 198 

Total cis-β-Carotene FSV-BT 0.027 0.020 0.012 0.051 

13-cis-β-Carotene FSV-DX 0.012 0.010 nq 0.076 

Total Carotenoids FSV-BT 0.566 0.804 0.261 1.063 

trans-α-Carotene NISTb 0.013 0.040 0.004 0.030 

δ-Tocopherol NISTb 0.095 0.107 0.037 0.181 

Legend for Tables 1, 2, and 3 

nd Not detected or reported as '0'
 

nq Not quantitatively determined (i.e., reported as 'trace', 'not determined', etc.)
 

<x Concentration at or below "limit of quantification" x.
 

Statistics (NIST's values are excluded from all calculations) 

n Number of laboratories reporting quantitative values for this analyte for this serum.
 

Min Minimum reported value.
 

Mean Average over all reported values.
 

Max Maximum reported value. 

SD Standard deviation over all values. 

CV Coefficient of Variation (% relative standard deviation): for (non-NIST) results: 100*SD/Mean 

Median Median over all reported values (i.e., 50% of values are larger, 50% are smaller.) 

eCV Estimated CV, based on the adjusted median absolute deviation from the median (MADe). 

The original report estimated eCV from the interquartile range (IQR). 

G8
 

All Lab Report Page 7 / 8 
All Laboratory Report for Round Robin XXXI
 

Lab Ret aToc bCar 

FSV-BA 1 1 2
 

FSV-BD
 1 2
 

FSV-BE
 2 1 2
 

FSV-BF
 2 3 4
 

FSV-BH
 4 4 1
 

FSV-BI
 3 2 2
 

FSV-BJ
 3 3 1
 

FSV-BK
 1 3
 

FSV-BL
 4 4
 

FSV-BM
 3 4
 

FSV-BN
 4 1 4
 

FSV-BO
 1 3 2
 

FSV-BP
 3 2 3
 

FSV-BQ
 3 4 1
 

FSV-BR
 2
 

FSV-BS
 

FSV-BT
 2 2 1
 

FSV-BY
 3 2 3
 

FSV-BZ
 1 4
 

FSV-CA
 4 4
 

FSV-CB
 4 4 3
 

FSV-CG
 4 4 3
 

FSV-CH
 4 4 3
 

FSV-CJ
 2 2
 

FSV-CK
 3 3 2
 

FSV-CO
 1 3 3
 

FSV-CP
 3 2
 

FSV-CQ
 4 3 4
 

FSV-CR
 1 1
 

FSV-CU
 2 3 4
 

FSV-CV
 1 1 1
 

FSV-CX
 2 1 4
 

FSV-CY
 1 2 4
 

FSV-DJ
 4 4
 

FSV-DK
 3 3
 

FSV-DL
 1 1 2
 

FSV-DS
 3 2 4
 

FSV-DX
 2 1 3
 

FSV-EA
 4 1 1
 

FSV-EC
 1 2 1
 

FSV-EK
 2 4 2
 

FSV-EX
 2 1 1
 

OA
 

1
 

1
 

4
 

3
 

3
 

2
 

4
 

2
 

3
 

3
 

1
 

3
 

4
 

4
 

4
 

2
 

2
 

4
 

4
 

1
 

2
 

2
 

1
 

3
 

2
 

1
 

1
 

3
 

1
 

gToc 

1
 

3
 

1
 

4
 

2
 

2
 

3
 

2
 

2
 

4
 

4
 

1
 

3
 

1
 

4
 

3
 

Table 5: Relative Rankings
 

Legend 

Lab Laboratory code 

Ret Relative Rank for: Retinol 

aToc Relative Rank for: a-Tocopherol 

bCar Relative Rank for: Total b-Carotene 

OA Overall Relative rank for labs that report Ret, aToc, and bCar. 

gToc Relative Rank for: g/b-Tocopherol 

Relative Rank 

An approximate measure of "closeness" to the interlaboratory medians for a given 

analyte in Round Robin XXXI. It is calculated as the PERCENTRANK of 

ABS(value-median)/median over all reported laboratory values for a given serum, 

averaged over all sera. The resultant average is itself ranked and scored as: 

1: among the 25% of reporting labs closest to the median 

2: not in the closest 25%, but in the closest 50% 

3: not in the closest 50%, but in the closest 75% 

4: among the 25% of reporting labs farthest from the median 

The "Overall" Relative Rank is calculated from the sum of the Relative Ranks of 

Retinol, a-Tocopherol, and total b-Carotene. The sum itself is ranked and scored 

as above. 

["PERCENTRANK" is an excel spreadsheet function. It returns the percentage 

standing of a given value among a set of values.] 

Note: "Relative Rank" does NOT measure "correctness, "goodness," etc. It 

reflects only a laboratory's relative agreement among its peers. Ideally, all 

analyses from all participating laboratories should agree within acceptable 

limits: the absolute variance evaluation for all labs could then be 

"Excellent" ... but the Relative Ranks would still go from "Closest" to 

"Farthest." 

G9
 

All Lab Report Page 8 / 8
 
Appendix H. Representative “Individualized Report” for RR31 

Each participant in RR31 received an “Individualized Report” reflecting their reported 

results. Each report included a detailed analysis of the results they reported for the 

following analytes: 

• Retinol 

• Retinyl Palmitate 

• α-Tocopherol 

• γ-Tocopherol 

• Total β-Carotene 

• trans-β-Carotene 

• Lutein 

• Lutein & Zeaxanthin 

• β-Cryptoxanthin 

• Total Lycopene 

• α-Carotene 

The following two pages are the “Individualized Report” for the analytes evaluated by 

participant FSV-NIST1 (listed as FSV-NISTa in the “All Lab Report”). 

H1
 
H

2
H

3
Appendix I. Shipping Package Inserts for RR32 

The following two items were included in each package shipped to an RR32 participant: 

• Cover letter 

• Datasheet 

The cover letter and datasheet were enclosed in a sealed waterproof bag along with the samples 

themselves. 

I1
 
[ 

[ 

[ 

[ 

[ 

[ 

[ 

[ 

[ 

[ 

[ 

[ 

[ 

[ 

[ 

L 

[ 

[, 

r. 

July 18, 1994 

Dear Colleague: 

NIST UNITED STATES DEPARTMENT DF COMMERCE 

Nat;ional lnat;lt;uta of St;andarda and Technology 

Gaithersburg, Maryland 20899-0001 

Enclosed is .the set of samples for Round Robin XXXII. You will find duplicate vials of four 

lyophilized sera samples for analysis along with a form for reporting your results. When reporting 

your results, please submit one value for each analyte for a given serum sample. If an obtained value 

is below the detection limit, please indicate this result on the form by using ND (Not Detected). For 

values not obtained, please leave a blank for the given analyte. Results are due to NIST by August 

30, 1994. The results from this study will be discussed at the Micronutrients QA Workshop, which 

will be held on Saturday, October 15, 1994 at the Crystal Gateway Marriott Hotel in Arlington, VA. 

(The details of the workshop were mailed to you last month). 

Samples should be reconstituted with 1.0 mL of HPLC-grade water or equivalent. We recommend 

that dissolution be facilitated with 3 to 5 minutes agitation in an ultrasonic bath or at least 30 min at 

room temperature with intermittent swirling. (CAUTION: Vigorous shaking will cause foaming and 

possibly interfere with accurate measurement. · The rubber stopper contains phthalate esters which will 

leach into the sample upon intermittent contact of the liquid sample with the stopper. These esters 

absorb strongly in the UV region and elute very near retinol in most HPLC systems creating analytical 

problems.) Pipette a known volume of serum from the vial for analysis since the final volume of the 

reconstituted sample is greater than 1.0 mL. For consistency, we request that laboratories use the 

following absorptivities (E 1 % cm) in ethanol: retinol, 1850 at 325 nm; retinyl palmitate, 97.5 at 325 

nm; a-tocopherol, 75.8 at 292 nm; y-tocopherol, 91.4 at 298 nm; a-carotene, 2800 at 444 nm; 

Jl-carotene, 2560 at 450 nm; lycopene, 3450 at 472 nm. 

Please mail or FAX your results for Round Robin XXXI to: 

Ms. Donna Sirk 

NIST 

Bldg. 222, Rm. B156 

Gaithersburg, MD 20899 

FAX: (301) 926-8671 

If you have questions regarding this round robin exercise; or have not received the information 

regarding the Micronutrient QA Workshop, please call me at (301) 975-3120 or mail/FAX queries to 

the above address. The results from Round Robin XXXI will be forwarded to you within two weeks. 

The results from the studies for ~-carotene in soy oil and the fat-soluble vitamins in food will be 

forwarded during that time as well. 

S cerely, 1 J .· / J t,' . t t-1u U / ___,---_,,, · (J]JU ,/7 

/ " 

eanice Brown Thomas 

Research Chemist 

Organic Analytical Research Division 

Chemical Science and Technology Laboratory 

Attachments 

I2
 
ROUND ROBIN XXXII RESULTS FROM LABORATORY # _________ 

DATE OF ANALYSIS ___________ 

RESULTS IN ug/mL 

SAMPLE NUMBER ANALYTE RESULT 

SERUM 199 RETINOL _____________ 

ALPHA-TOCOPHEROL _____________ 

VIAL # ___ BETA-CAROTENE _____________ 

SERUM 200 RETINOL _____________ 

ALPHA-TOCOPHEROL _____________ 

VIAL # ___ BETA-CAROTENE _____________ 

SERUM 201 RETINOL _____________ 

ALPHA-TOCOPHEROL _____________ 

VIAL # ___ BETA-CAROTENE _____________ 

SERUM 202 RETINOL _____________ 

ALPHA-TOCOPHEROL _____________ 

VIAL # ___ BETA-CAROTENE _____________ 

OPTIONAL ANALYTES: SUPPLY ONE RESULT IF AVAILABLE 

SERUM # 199 200 201 202 

TRANS-BETA CAROTENE 

ALPHA-CAROTENE 

RETINYL PALMITATE 

GAMMA-TOCOPHEROL 

LYCOPENE (TOTAL) 

9-CIS-BETA CAROTENE 

13-CIS-BETA-CAROTENE 

LUTEIN 

ZEAXANTHIN 

BETA-CRYPTOXANTHIN 

DIRECTIONS: 

RESULTS DUE BY: August 30, 1994 

FAX RESULTS TO 301/926-8671 

I3
 
 

 

 

 

 

Appendix J. Final Report for RR32 

A preliminary report for RR32 was sent to all participants shortly before the QA 

Workshop held on October 15, 1994. Based upon feedback from the Workshop 

participants, the format used in the “All Lab Report” for RR32 was significantly revised 

before the Final Report was distributed. 

The following 15 pages include: 

•	 The cover letter sent with the preliminary report. Since the preliminary report 

itself did not reflect all RR32 results, it is not reproduced. 

•	 A reconstruction of the Cover letter sent with the Final Report. The original text 

of this letter has been lost; this version is based on an extant year-end summary 

report, statements in the “Lies, Damn Lies, and Statistic” document for RR32, and 

the report format used in RR33. 

•	 A discussion entitled “Lies, Damn Lies, and Statistics” that: 

o	 describes the nature of the test samples and details any previous distributions 

o	 summarizes aspects of the study that we believe may be of interest to the 

participants 

•	 A listing and graphical presentation of (Total) Retinol, α-Tocopherol, and Total 

β-Carotene summary statistics for all samples that were distributed more than 

once from RR01 through RR32. This material was presented at the QA 

Workshop and included (without further discussion) in the documentation packet 

sent to all participants. Figures 3 to 5 in this material were originally distributed 

in grayscale; the colored originals are reproduced here. 

The “Lies, Damn Lies, and Statistics” states that the documentation packet for RR32 

contained revised format “All Lab Reports” for RR30 and RR31. As the data in the 

reformatted reports is identical to that in the versions provided in Appendices C and G of 

this document, the revised “All Lab Reports” for RR30 and RR31 are not reproduced. 

J1
 
J2
 

 

 

 

 

 

 

 

 

 

 

 

U N I TE D ST A T ES D EP A R TM E N T O F C O M M ER C E 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-0001 

October 28, 1994 The original text of this letter has been lost. This version has 

been prepared from an extant year-end summary report. 

Dear Colleague: 

Enclosed is the summary report of the results for Round Robin XXXII (Serum 199-202). Serum 

199 was previously distributed in Round Robin XXX. Sera 200-202 are from serum pools for a 

renewal material, Standard Reference Material 968b, Fat-Soluble Vitamins and Cholesterol in 

Human Serum, which will be available next year. 

The average estimated coefficient of variation (eCV) for Round Robin XXXII is about 9 % for 

retinol, 7 % for α-tocopherol, 10% for γ-tocopherol, and about 14 % for total β-carotene. The 

average eCV for retinyl palmitate is approximately 27 %. This variation is due to the difficulty 

of making measurements at levels that are <100 parts-per-billion, as indicated in Serum 199 

where the eCV is 63 % and 66 % in Round Robin XXX. We will continue to improve the 

measurement quality of retinyl palmitate and the major carotenoids as well. 

Data for evaluating your laboratory’s performance in Round Robin XXXII are provided on page 

5 of the attached Round Robin XXXII report. The criteria used to summarize laboratory 

performance is as follows: results rated 1 (within ± 1 SD of the median value) indicate 

EXCEPTIONAL performance, those rated 2 (within ± 2 SD) indicate ACCEPTABLE 

performance, a rating of 3 (within ± 3 SD) is MARGINAL performance and 4 (>3 SD of the 

median) indicates POOR performance relative to the current state-of-the-practice. 

If you have concerns regarding your performance or were rated "POOR" based on the 

convention stated above, we suggest that you obtain a unit of SRM 968a, Fat-Soluble Vitamins 

in Human Serum, and analyze all three levels. If, with minor method modifications your 

measured values do not agree with the certified values, feel free to contact us for consultation. 

As last year, the fees for non-NCI funded laboratories will be $300 for US labs and $600 for 

non-US labs. An invoice to that effect will be mailed to those laboratories. 

The 1995 program will consist of three round robin exercises for the analysis of fat-soluble 

vitamins and carotenoids in serum, three studies for the analysis of ascorbic acid in serum, and 

two exercises for the analysis of fat-soluble vitamins and carotenoids in food. The first set of 

samples for the fat-soluble vitamins in serum analysis will be distributed the week of January 23. 

Results are due march 20; written feedback will be provided to labs by April 24. The second set 

of samples will be shipped the week of April 24 with results due by June 16 and feedback to labs 

by July 24. The third set of samples will be shipped the week of July 24 with results due by 

September 15 and feedback by October 20. 

The round robin studies for the analysis of fat-soluble vitamins and carotenoids in food will also 

be scheduled in April and July to coincide with the second and third fat-soluble vitamins in 

J3
 
 

 

serum round robin studies. The coordinator of these exercises is Dr. Katherine Sharpless 

(301-975-3121). 

The first set of samples for the analysis of ascorbic acid in serum will be distributed in January. 

The second and third sets will be distributed in April and July, respectively. These round robin 

studies are being coordinated by Dr. Sam Margolis (301-975-3137). 

As a result of our efforts to provide consultation services in methods development and 

refinement a methods manual, Methods for Analysis of Cancer Chemopreventive Agents in 

Human Serum, has been completed and will be available upon request in the coming year. Also, 

at the past QA workshop it was suggested that a certificate of participation for the QA program 

be distributed to the laboratories. We are currently working on this and will distribute 

certificates in December or early January. Another topic of discussion at the workshop was the 

need to broaden the scope of the program to include a larger segment of the clinical community. 

In response, we will explore the possibility of holding future QA workshops at national meetings 

to include a broader audience. 

If you have questions, please contact me at 301-975-3120. 

Sincerely, 

Jeanice Brown Thomas 

Research Chemist 

Organic Analytical Research Division 

Chemical Science and technology Laboratory 

Enclosures 

J4
 
\_ 

(_ 

( 

"Lies, Damned Lies, and Statistics" 

Mark Twain 

The attached Round Robin XXXII Report is very similar to RR XXXI' s, with some format 

simplification in the "All Lab" data summary and a major change in (what was) the 

"Relative Performance Summary" page ... 

Simplification: The "All Lab" report now presents all data for each analyte on a single 

page, with as many analytes on a page as will conveniently fit. Page 4 lists the analytes 

reported by only a single (non-NIST) lab, as well as the Legend. 

Major chan~e: Due to popular request, the ranking method used in the "Relative 

Performance Summary" (i.e., ±of you getting a "1 ", ~a "4") has been replaced with a 

"standard score" related to how many standard deviations away from the median you are. 

It's now possible for everyone to score well. The new name for this page 5 of the "All Lab 

Report" is the "lnterlaboratory Measurement Comparability Summary." Details of the 

calculation are provided on page 5, just to the right of the scores. 

Freebie: Complete "All Lab Reports" for RRs XXX and XXXI analogous to the new RR 

XXXII report are included in your packet. 

Same-as-before: The "Individualized" report's first six pages are identical to those of 

Round Robin XXXI (except that RRs XXIII - XXXI are now the reference period). 

Pa e Contents 

1 Your lab's data table 

2 %Bias barchart for retinol 

3 %Bias barchart for ex- and y- tocopherol 

4 %Bias barchart for total and trans-~-carotene 

5 Interlaboratory median vs. your value scatterplots for retinol, ex- and ytocopherol, total and trans-~-carotene 

6 (Provisional) Performance Summary 

7 Comparison plots for retinol, retinyl palmitate, ex- and y- tocopherol, total and 

trans-~-carotene. 

8 Comparison plots for total ex-carotene, ~-cryptoxanthin, lycopene, lutein, 

zeaxanthin, and lutein & zeaxanthin 

The "Comparison to Known Relationships" on pages 7 and 8 cheat somewhat, as only 

serum 199 was a replicate (serum 192 from RR XXX). Sera 200 to 202 are new, with no 

established relationships among them: they're included in the graphs mostly because it was 

easy to do so ... and maybe the per-serum comparison of your data to the group's is 

interesting? 

J5
 
In RR XXX's report, the interlaboratory median was shown to be very similar to the 

"Trimmed Core" mean values used in prior years. In RR XXXI's report, the "estimated 

standard deviation (eSD)" - defined as 0.74*(interquartile range) - was shown to be 

midway between the simple SD and the "Trimmed Core" SD. As the simple SD is too big 

(some of you are outliers ... ) and the "Trimmed Core" SD is too small (throw away enough 

data and there is no variation), being midway is ok. 

Now "to compare variation over analytes, concentration ranges, and time ... " First, let's 

look at reproducibility over concentration. Figure 1 plots Median vs eSD for retinol, a.­

tocopherol, and total ~-carotene over three time periods: RR I-XIII, RR XIV-XXI, and RR 

XXII-XXXII. Measurements were clearly less reproducible across laboratories during the 

first period for all three of these analytes, with no real difference between the second and 

third periods. (No data is available for y-tocopherol for the first period.) Interestingly, the 

slope of the regression lines for retinol, a.-tocopherol, and total ~-carotene for the combined 

second and third periods are all about the same: 

log10(eSD) =Constanta+ 0.83*log10(Median) or 

eSD = 10CConstanta )(Median0.83) 

where the "Constanta" is specific to each analyte. This relationship is shown as a dotted 

line in Figure 1. Note that the slope is 0.83, .n.Q1 1.00: the eCV (estimated Coefficient of 

Variance, lOO*eSD/Median) is .n.Q1 constant for all concentrations. The eCV is larger at 

low concentrations and smaller at high concentrations. 

This really isn't surprising - why should CV be constant over all concentrations? But it 

does make estimating average interlaboratory reproducibility over time more difficult: the 

analyte levels of the sera affect the expected reproducibility for a given RR. To correct for 

this, we must adjust the observed eCV at its observed median to its expected value at some 

fixed median, using the above relation for each analyte. A convenient and fairly 

representative fixed median is the average of all observed medians. 

Figure 2 plots a highly smoothed time series of adjutsed eCV values over all Round 

Robins, with some interesting timepoints noted. Bottom line? Interlaboratory 

reproducibility for RR samples was best when common control sera were being used (but 

how representative of real day-to-day performance was this?) Reproducibility has declined 

( 

slightly since that time, but is clearly much better than the first few years. Perhaps a (-

reproducibility plateau has been reached for all four analytes in the past year or so. 

J6
 
( 

( 

The Round Robin XXXIII Report will present an approach to documenting measurement 

consistency over time, not just reproducibility. 

Once again, your comments and suggestions are welcome. If you discover any errors in 

our recording or interpretation of your data, please let us know! 

"::-~ 

' '~ ' 

01-~ Dave Duewer 

Research Chemometrician 

301-975-3935 

DLDuewer@enh.NIST.gov 

. -// ' , ~·~- ~ ti ~./c.?1 (..-; ~'V(.., 

Margaret Kline 

Research Biologist 

J7
 
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Retinol , , 

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·X. 

~-Carotene 

1 1 

Median Concentration, μg/mL 

-1 RR 1-13 

-~ RRl4-21 

-3 RR22-32 

RR 14-32 Global Slope= 0.827 

Figure 1 

Interlaboratory Median vs eSD 

10 

, , 

cx-Tocopherol 

, 

y-Tocopherol 

for Retinol, Total ~-Carotene, and ex- and y-Tocopherol 

, 

1 

3 

, 

0.1 

J8
 
Percent 

30 

20 

10 

t 

11/84 

10 

E > 

Free Controls 

20 

Round Robin 

- Retinol, 0.55 μg/mL 

- a-Tocopherol, 7.5 μg/mL 

-y-Tocopherol, 1.8 μg/mL 

- ~-Carotene, 0.50 μg/mL 

Figure 2 

SRM968 

Interlaboratory Precision over Time 

for Retinol, Total ~-Carotene, and a- and y-Tocopherol 

30 

t 

9/94 

J9
 
RR Date Serum n 

01 10/1/ 84 5a 16 

6a 16 

7a 16 

02 1/30/85 l Ba 18 

19a 18 

03 4/1 /85 6 18 

7 18 

B 18 

9 18 

05 10/1/85 19 21 

20 23 

21 23 

07 6/1/86 31 24 

32 21 24 

33 27 

34 28 

35 34 27 

44 33 28 

08 10/1/86 50 26 

51 26 52 26 

09 3/1/87 62 27 

63 27 

64 27 65 27 

66 27 

11 10/1 /87 72 63 23 

73 52 23 

74 65 23 75 50 23 

76 51 23 

Summary Results for all Sera 

Round Robin Intercomparisons I - XXXII 

Retinol a - Tocopherol -

Mean CV NIST Med eCV n Mean CV NIST Med eCV 

1. 01 56 0. 90 0.85 8 11 9.1 12 10. 0 9.0 10 

2. 40 38 2. 16 2 . 11 16 11 4.1 60 3.4 3.4 10 

3 . 82 44 3 .75 3.25 16 11 25.8 34 25.1 25.3 10 

0.54 32 0. 51 0.53 12 12 6.3 12 6 .3 6.3 8 

1. 57 21 1.52 1.47 15 12 12. 6 12 12 . 7 12. 2 6 

1. 54 40 1. 35 1. 33 20 12 11. 8 63 11. 0 8.9 35 

1. 04 46 0.89 0.87 24 12 8.6 62 7.1 7.1 28 

0 . 38 40 0.37 0 . 34 25 12 3.1 64 2.6 2.4 39 

1. 33 51 1. 25 1.16 21 12 9.1 64 7.2 7. 0 60 

0. 52 2 8 0.44 0.51 11 15 30.4 27 33 .8 29.6 11 

0.48 25 0.43 0.46 9 16 7. 0 27 7. 7 7.0 12 

0 .44 28 0 . 38 0. 42 14 16 6.4 31 7.6 6 . 3 17 

0.75 23 0. 77 0. 77 13 20 11.2 18 11. 9 11.9 15 0.41 24 0.43 0.41 12 20 6. 3 15 6 . 1 6. 3 12 0.35 32 0.36 0 . 35 13 23 6 .J 24 6.6 6. J 17 

0 .36 30 0. 35 0.3 5 18 23 6.3 17 6 .7 6.1 15 

0 .35 30 0. 36 0. 34 18 23 6.2 24 6.7 6. 3 13 

0 . 37 31 0.35 0 . 36 15 23 6. 2 20 6 . 7 6. 3 16 

0.41 41 0. 37 0. 39 13 22 9 .3 26 8 . 6 8.4 14 0.46 34 0.44 0 . 43 10 22 7 .2 22 7. 1 7.0 14 

0.94 34 0 . 94 0 . 91 16 22 10. 7 21 10.6 10 . 3 14 0.30 25 0. 33 0. 29 20 24 10.9 14 11.1 10.4 11 

0 . 88 21 0. 92 0.88 15 24 7.1 16 6.7 6.8 13 0 .57 20 0 . 60 0 .57 16 24 5.0 24 4 .8 4. 7 14 

0.46 19 0. 48 0.44 16 24 9. 5 12 9.3 9. 3 10 

0.80 24 0. 81 0.78 19 24 8 .9 14 8.1 8 .4 13 

0 . 87 17 0.92 0.89 14 20 6. 9 19 6.8 6.6 7 

0 . 97 17 0. 97 0 . 97 8 20 11.3 22 10.9 10.7 12 

0.46 19 0.47 0.44 11 20 9.2 21 9.4 8.9 16 

0. 40 18 0 .39 0.40 10 20 9.1 22 9.0 8.6 10 

0 . 45 20 0. 44 0.45 11 20 7.3 21 7.3 6. 9 9 

Total b-carotene 

n Mean CV NIST Med eCV 

12 1. 53 42 1.16 1.19 59 

12 5. 51 25 5.06 5.19 16 

12 6. 20 21 4. 30 6.00 22 

13 0. 70 83 0. 53 0.45 26 

13 2.72 37 2 .83 2.28 34 

10 0. 37 76 0 . 09 0. 36 69 

12 0 . 21 88 0.40 0.14 150 

5 0.10 101 0.13 0 . 09 54 

11 0 . 28 99 0.14 0.2 4 139 18 0.50 41 0. 39 0.49 32 

19 0 .14 41 0 .12 0.13 34 

19 0. 41 33 0.34 0.42 21 

17 0.19 103 0 . 12 0.14 11 

17 0. 46 51 0.40 0.45 24 

20 0 . 16 133 0 . 07 0 . 10 21 

20 0. 26 74 0 . 16 0.20 23 

20 0.25 72 0.16 0.20 31 

20 0 . 14 129 0 . 06 0 .09 26 

18 0. 09 40 0.07 0.09 38 

18 1.17 34 1. 04 1.05 24 

18 0 . 64 29 0 . 56 0 .62 19 19 0.15 27 0 . 14 0.15 12 

19 0. 91 25 0.88 0.92 14 19 0 . 07 22 0. 07 0.06 19 19 0 . 40 21 0.38 0 . 41 13 

19 1. 37 28 1. 21 1. 41 17 

16 1. 07 37 0 .86 0.98 12 

16 0. 69 37 0.55 0. 64 13 

16 0.47 38 0.36 0.44 17 

16 0 . 09 38 0.07 0 . 08 16 

16 1.30 37 1.01 1.17 15 

All_.Sera_Summary (10/7/94) 1/4 

J10
 
RR Date Serum n 

12 2/29/88 77 D 31 

78 A 31 79 31 

80 c 31 81 B 31 

13 6/1/88 90 28 

91 D 28 92 28 

93 28 94 B 28 

14 10/1/88 95 92 23 

96 66*1.2 23 97 62*1.2 23 98 92 23 99 64 *1.2 23 

15 3/1/89 100 28 

101 28 102 28 

16 6/1/89 109 90 27 

110 79 27 111 93 27 

112 B 27 

17 10/1/89 115 62*1. 2 30 

116 30 

117 64*1.2 30 

118 30 119 66*1. 2 29 

18 3/1/90 120 30 

121 30 122 30 

Summary Results for all Sera 

Round Robin lntercomparisons I - XXXII 

1 herol 

Mean CV NIST Med eCV n Mean CV NIST Med eCV 

1. 05 21 1. 01 1. 07 10 28 9.1 16 9.5 9.2 17 

0.40 16 0.36 0.40 11 28 5.5 15 5 . 7 5.5 16 0.38 23 0.34 0.37 11 28 5.8 15 6.1 5 . 8 14 0.96 23 0 . 90 0.97 12 28 10.2 14 10.7 10.3 11 0.45 17 0. 41 0. 4 4 11 28 6.0 15 5.7 6.0 15 0.40 9 0 . 38 0.39 10 26 7.0 9 7.0 6.9 8 

1. 03 8 1. 00 1.02 7 26 9.4 9 9.4 9 . 3 8 

0 . 59 11 0.57 0.58 7 26 6 .o 11 5 . 9 6.0 9 

0.75 8 0.70 0. 75 6 26 4.9 11 4.6 4.9 10 0. 44 13 0.41 0.43 6 26 6.0 10 5.9 5.9 10 

0. 59 12 0.57 6 21 5.8 24 5.7 8 

0.91 8 0.89 4 21 9.3 7 9.2 4 0.36 19 0.35 7 21 11. 7 9 11.8 J 0.58 9 0 .58 4 21 6.0 20 5.8 6 

0. 64 13 0.65 6 21 5.4 12 5 . 4 7 

0.31 7 0.31 0. 31 6 26 5.0 10 4.9 4.9 8 

0.47 8 0.47 0.47 8 26 7. 7 10 7.3 7.9 5 

1.18 9 1.17 1. 16 7 26 12. 3 8 11. 9 12 . 5 6 

0.41 23 0.39 0 . 39 8 25 7.0 7 6.8 7.1 3 0.40 43 0.33 0.36 9 25 6. 0 11 5 . 6 5.9 6 0.79 26 0.73 0.76 4 25 4.9 9 4.4 5.0 5 

0 .46 26 0.38 0.43 8 24 6 . 0 7 5.4 6.0 4 

0.39 31 0 . 36 0 .35 12 25 11.5 14 12 . 0 1 1.9 6 

1. 07 22 1. 06 1.00 11 25 7.6 10 7.5 7 . 7 9 

0 .69 20 0 .66 0.66 6 25 5.4 7 5 . 3 5.4 6 

0 . 54 15 0.49 0.51 10 24 10.1 14 10.1 10 .3 6 

0 . 93 19 0.98 0.89 7 24 9 . 3 12 9.2 9.4 7 

0 . 26 11 0.28 0.26 8 29 4.8 7 5.0 4.8 6 

0.50 16 0.52 0.50 6 29 6. 7 13 7.2 6.6 7 0.89 23 0 . 91 0.85 7 30 9.4 13 9.2 9.3 8 

1 b 

n Mean CV NIST Med eCV 

20 0.99 23 1.05 1.00 15 20 0 . 20 19 0 . 20 0.21 10 

20 2.58 2 4 2.54 2.51 16 

20 0.85 20 0.77 0.85 16 20 0 . 20 25 0 .22 0 . 21 22 

18 0 . 09 JO 0 . 09 0 . 08 24 18 1. 00 15 1.12 0.96 13 18 1.24 17 1.33 1.19 16 

18 0. 35 17 0.33 0.34 8 

18 0.21 19 0.22 0.20 13 15 1. 28 10 1.28 10 15 1. 70 7 1. 72 9 

15 0 . 18 7 0.18 4 

15 1. 28 1 0 1.25 8 

15 0 . 09 21 0.08 8 16 0 .11 13 0.14 0.11 7 16 0. 66 7 0.66 0.67 6 

16 1. 48 7 1.40 1.50 6 17 0. 08 28 0.09 0.08 19 17 2. 57 22 2.45 2.47 12 

17 0 .37 24 0 . 30 0.34 12 17 0. 21 26 0.18 0.21 14 

18 0. 21 36 0.15 0.19 10 18 1.11 10 0.97 1.08 8 18 0.11 80 0 . 07 0 . 09 23 

18 0.52 14 0.40 0.51 10 18 1. 68 8 1.36 1.65 5 

21 0.41 12 0.49 0.41 13 21 1. 00 20 0. 63 1. 05 10 21 1. 96 18 1.60 1.94 18 

All_Sera_Summary 00/7/94) 214 

J11
 
RR Date Serum n 

19 6/1/9 0 1 30 36 

131 37 

132 37 13 3 37 

2 0 10/22 /9 0 138 28 

139 28 

140 133 29 

141 122 29 142 130 29 

21 3/1/91 144 c 34 

145 121 34 

146 131 34 

147 120 34 

22 7/9 /91 148 968aL 45 

149 968aM 45 

150 968aH 45 

23 9/1 /91 1 55 44 

156 44 

157 44 

159 968aM 43 

24 3/6 /92 160 157 43 

1 61 968aH 44 

162 132 44 

163 A 44 

25 6/26/92 164 D 31 

165 12 2 31 

16 6 131 31 

167 968aL 31 

26 10 /16/92 168 138 34 

169 139 34 

170 35 

171 35 172 170 35 

Summary Results for all Sera 

Round Robin Intercomparisons I - XXXII 

Retinal a-Tocopherol -

Mean CV NIST Med ecv n Mean CV NIST Med eCV 

0.24 21 0.21 0.23 11 34 4.0 45 3.3 3.8 6 0.52 22 0.52 0.51 10 34 6.3 23 6.8 6.6 7 

0 .3 0 17 0.31 0.29 7 34 4.4 2 4 4.4 4.6 7 

0.76 17 0.82 0.75 7 34 11.2 21 11. 5 11. 9 8 0. 54 17 0.58 0.55 9 30 10.4 12 10. 6 10.3 10 

0 . 62 15 0 . 67 0 .63 9 3 0 9.7 8 10 .1 9.7 6 

0.72 13 0.83 0.73 8 31 11.6 11 11. 4 11. 6 5 

0.80 17 0.90 0.80 12 31 9.5 14 8.9 9.6 10 

0 .22 12 0 .23 0.23 9 31 3.9 16 3.3 3.7 8 

0.96 16 0 . 92 0.96 8 35 10.7 8 10.4 10.7 5 

0.50 16 0.49 0.50 7 35 6.9 8 6.6 6.9 5 

0 .54 19 0 . 52 0 . 52 11 35 6.6 11 6.3 6.7 7 

0.28 23 0. 25 0 . 26 8 35 s.o 13 4.6 4.9 8 

0.20 31 0.17 0.19 11 45 4. 7 17 4. 5 4.7 11 

0 .49 20 0 .50 0.50 9 45 10.2 17 10 . 3 10.5 4 

0.75 91 0.63 0.6 6 10 45 16.0 13 16. 2 16.6 5 

0. 53 15 0. 57 0.53 9 44 7. 5 13 7.6 7.4 6 

0.40 15 0.41 0.40 11 44 10.0 14 9 . 8 10 .0 8 

0 .98 16 0 . 99 0.98 10 44 6.3 14 6.4 6.3 8 

0.50 18 0. 52 0.50 10 43 10.5 15 10.4 10. 5 7 

1. 01 23 0.91 1.02 7 41 6.3 13 5.9 6.3 8 

0 .68 14 0.60 0.68 9 42 1 5.9 11 15.9 16. 0 9 

0 .29 1 8 0- 28 0.29 7 42 4. 6 13 4. 3 4.6 9 

0. 39 13 0 . 34 0.39 9 42 5. 7 13 5.1 5.6 8 

1. 07 10 0 . 99 1. 07 9 33 9. 7 13 9.6 9.4 6 

0. 89 12 0.86 0.87 10 33 9.8 9 9.5 9.8 7 

0.54 12 0.52 0.53 7 33 6. 7 15 6.5 6.5 7 

0 . 20 ·20 0 .17 0 .19 12 33 4. 8 16 4. 5 4.8 9 

0.55 u 0 . 55 0.55 6 36 10.5 10 10.1 10.5 7 0. 64 14 0. 66 0.63 6 36 9. 6 12 9.9 9.7 6 

0 .67 7 0 . 69 0 . 67 5 37 6 .2 10 6.5 6.2 1 0 

0 . 55 8 0.51 0.54 5 37 4.9 11 4.8 5.0 10 

0.67 7 o. 72 0.67 5 37 6.1 10 6.2 6.2 9 

Total b-Carotene 

n Mean CV NIST Med eCV 

25 1.00 25 0.98 0.96 11 24 0. 23 66 0.21 0.19 12 25 1.14 29 1.11 1. 11 7 25 0.55 30 0. 5 0 0.53 8 21 1. 70 31 1. 97 1. 67 14 21 0 .44 12 0 .70 0.44 13 22 0. 52 15 0. 51 0.50 11 22 1. 90 30 1.58 1.82 26 

22 0 . 91 20 0.95 0.89 7 

24 0.84 30 0.80 0.84 7 

24 1.14 28 1. 04 1.11 10 

24 0 .24 66 0 .20 0.19 12 

24 0.45 27 0.40 0 . 43 13 

34 0 .27 35 0.23 0.25 29 34 0.88 17 1.05 0.89 14 34 2.31 1 5 2.86 2.2 5 14 

30 0.35 28 0. 42 0. 37 22 

31 0.79 23 0.85 0.85 19 31 0 . 09 42 0.09 0.09 32 

30 0.86 31 0.79 0.90 18 

33 0 .10 38 0.09 0.09 24 

34 2. 19 33 2.40 2.18 15 

34 1. 02 22 1.12 1. 03 15 34 0.18 22 0.20 0.18 12 

29 1. 09 35 1. 06 1. 05 14 28 2. 09 25 1. 5 6 2.02 17 

29 0 .22 113 0.21 0.18 18 28 0 . 30 68 0.22 0.26 15 

31 1. 66 17 1. 59 1. 66 14 

31 0. 43 23 0 .45 0. 44 18 

32 0 . 62 17 0.66 0 . 60 15 32 0. 40 16 0. 48 0.39 16 

32 0 . 61 16 0.61 0.58 14 

All_,Sera_Summary (IOl7/94) 3/4 

J12
 
RR Date Serum n 

27 3/1/93 173 968aM 46 

174 155 46 

175 156 46 

176 171 46 

177 968aH 26 

28 6/1/93 181 44 

182 43 183 44 

184 44 

185 182 44 

29 9 /1/93 186 130 46 

187 121 45 188 133 46 189 139 46 

190 138 46 

30 3/19/94 191 40 

192 43 

193 43 

194 42 

31 6 / 14/94 195 198/ 2 37 

196 183 37 197 198 / 4 37 

198 38 

32 8/30/94 199 192 36 

200 968bL 36 

201 968bM 36 

202 968bH 36 

Summary Results for all Sera 

Round Robin Intercomparisons I - XXXII 

-

Retinal a - Tocopherol 

Mean CV NIST Med eCV n Mean CV NIST Med eCV 

0.50 17 0 .52 0.50 8 42 10.6 13 10.8 10.5 8 0.54 18 0.54 0.54 10 42 7.4 15 7.5 7.6 9 

0. 41 16 0.41 0.40 8 42 10.1 14 9.8 10.1 10 

0.55 15 0.56 0.54 10 42 4.9 15 4.7 4.9 10 0. 67 16 0.63 0 .66 9 24 15. 7 8 15.8 15.8 7 

0.50 23 0 .41 0.48 13 44 6. 7 22 7 .4 7.1 7 o. 54 17 0.51 0.55 9 43 5.3 22 5.7 5.5 7 

0. 57 24 0. 50 0.56 9 44 10. 7 23 11.7 11.2 9 

0. 37 25 0.37 0.36 10 44 4.3 29 4.5 4.3 7 

0.56 23 0.50 0.55 11 44 5 .3 25 5. 7 5.5 8 

0 . 22 22 0.23 0.22 12 47 3.5 24 3 . 6 3.7 10 

0.50 20 0.50 0 .49 7 46 6 .5 24 6.6 6 . 7 8 

0. 72 15 0.70 0.73 6 47 11 .2 22 11.4 11.5 9 0. 63 14 0.61 0.63 5 47 9 .3 22 9.3 9.5 6 0. 54 15 0.54 0.55 8 47 10. 1 23 10.1 10.2 7 

7.07 27 6.99 6.85 13 42 23. 8 20 22.0 24 . 0 12 

1.16 23 1.12 1.11 15 43 7.3 14 6.9 7.3 9 

1. 05 24 0.93 1. 03 9 43 27 .1 17 26.0 27.1 10 

0.45 25 0.44 0 .43 8 42 7 . 3 12 7.3 7 . 3 8 

0 .37 17 0 .38 0 . 38 11 38 7.0 17 6 . 6 7. 1 12 

0.5 5 15 0.56 0. 55 9 38 11.4 1 5 10.9 11.5 7 

0 .19 19 0.19 0.20 13 38 3.6 22 3.4 3.7 15 

0. 71 15 0.71 0.73 9 39 14.0 16 13. 5 14 .2 8 

1. 08 11 1. 06 8 38 7.1 16 7.2 6 

0.31 16 0.30 9 38 7.0 19 7.1 8 0.52 10 0.51 8 38 9 .8 16 10. 0 6 

0. 89 12 0.88 9 38 17 . 4 16 17. 7 8 

Total b-Carotene 

n Mean CV NIST Med eCV 

38 0.91 25 0 . 89 0.91 10 

39 0.40 53 0.32 0.37 20 39 0 .85 35 0.69 0.83 18 

39 0.42 39 0.32 0.41 18 

23 2 .37 18 1.95 2.3 6 16 

33 0. 14 105 0.10 0 . 09 26 33 0.46 39 0.39 0.43 16 33 0.39 42 0.39 0.37 19 32 0. 37 33 0.37 0.3 5 13 33 0 .45 36 0 . 41 0.42 19 38 0 . 93 42 0 . 96 0.93 15 38 1. 07 49 1. 21 1.05 15 38 0.50 41 0.56 0.49 12 38 0. 43 38 0.50 0.43 19 38 1. 64 43 1. 60 1. 65 17 34 1. 63 21 1. 62 1. 64 12 34 0. 60 21 0.5 5 0.60 16 

34 0.39 37 0.37 0.37 18 31 0.08 113 0.05 0.06 35 

29 0.34 22 0 .36 0 . 34 14 29 0 .35 21 0 .36 0.35 16 29 0.15 31 0.16 0.15 21 

30 0. 67 17 0.69 0.67 12 

29 0.57 17 0.59 12 29 0.25 24 0.25 16 29 0.6 0 19 0.61 12 29 1.20 19 1.23 16 

AILSera_summary (lonJl)4) 4/4 

J13
 
,,,-. 

Figure 3 

lnterlaboratory Retinol Measurement of Replicate Samples 

0.9 

0.8 • 0.7 

..-... 

] 0.6 • 

...._ 

0.0 

.... 0.5 -'-

"-' 

0 

i:: 0.4 

·.o 

0.3 0.2 

-

. 

0 Ei3 

6LJ g--g 

rn • • 

Cl &8 5 10 I 15 20 25 30 < 0\ '° 

..,.. 

Round Robin NIST . 0 rn Mcdmn 

u 25% 

;,... 

Number of Lah<mttori'-'11 

J14
 
) 

] 10 

bl) -- 9 :t 

"-" 

0 8 I 

(J) 

: 1 

'& 

0 

u 

0 

I 

5 

4 

0 

Figure 4 

Interlaboratory a-Tocopherol Measurement of Replicate Samples 

Fil D r-i 

• 

H 

l!J 

BB @ 

e 

. Fl 

fill 

• • 

..... 

en 

Cl 

5 10 I 15 20 25 30 

] 

§ Round Robin NIST Median en 

u 25% 

.. 

Number of Laborntorics 

( 

J15
 
,.......... 

) 

00 --

:i. 

""-' 

Q) 

i::: 

Q) 

0 

a 

u 

I 

01 

ca 

0 

f-4 

3 

2 

0.8 0.7 

0.6 0.5 0.4 0.3 

0.2 

0.08 0.07 

0.06 

(' 

Figure 5 

Interlaboratory Total f3-Carotene Measurement of Replicate Samples 

ui 

• 

8 

•! 

Fi D 

• 

Ll 

B B 

B Q ! B 

00 

5 10 q 15 < 

0 

• 

D 

• • [!] 

• • t:j 

rei 

D 

Et@ 

20 25 

.... 75% 

b Round Robin r;;i Median § Cl) 

u 25% 

;.::-

Number of l..alxmatori4-'fl 

30 

J16
 
 

Appendix K. “All-Lab Report” for RR32 

The following five pages are the “All-Lab Report” for RR32 as provided to all 

participants, with the following exceptions: 

•	 the participant identifiers (Lab) have been altered. 

•	 the order in which the participant results are listed has been altered. 

•	 the robust standard deviation (eSD) has been recalculated using a more efficient 

robust estimator: the adjusted median absolute deviation from the median 

(MADe) rather than the adjusted interquartile range (IQR). 

•	 the robust coefficient of variation (eCV) has been recalculated using the
 

recalculated eSD.
 

•	 The “Interlaboratory Measurement Comparability Summary” scores have been 

recalculated using the recalculated eSD 

The data summary in the “All-Lab Report” has been altered to ensure confidentiality of 

identification codes assigned to laboratories. The only attributed results are those 

reported by NIST. The NIST results are not used in the assessment of the consensus 

summary results of the study. 

K1 
Lab 

Round Robin XXXII Laboratory Results 

Results in ug/mL 

Total Retinol 

199 200 201 202 

Retinyl Palmitate α-Tocopherol γ/β-Tocopherol δ-Tocopherol

FSV-BA
 

FSV-BD
 

FSV-BE
 

FSV-BF
 

FSV-BH
 

FSV-BI
 

FSV-BJ
 

FSV-BK
 

FSV-BL
 

FSV-BM
 

FSV-BN
 

FSV-BO
 

FSV-BP
 

FSV-BQ
 

FSV-BT
 

FSV-BX
 

FSV-BY
 

FSV-BZ
 

FSV-CA
 

FSV-CB
 

FSV-CH
 

FSV-CK
 

FSV-CL
 

FSV-CM
 

FSV-CO
 

FSV-CQ
 

FSV-CR
 

FSV-CT
 

FSV-CU
 

FSV-CV
 

FSV-CX
 

FSV-CY
 

FSV-DJ
 

FSV-DK
 

FSV-DL
 

FSV-DS
 

FSV-DU
 

FSV-DX
 

FSV-EA
 

FSV-EC
 

FSV-EK
 

FSV-EX
 

FSV-FD
 

1.020 0.291 0.504 0.855 

1.137 0.308 0.512 0.878 

1.155 0.301 0.554 0.945 

1.098 0.311 0.540 0.890 

0.899 0.301 0.505 0.776 

1.027 0.281 0.507 0.873 

1.049 0.285 0.513 0.861 

1.056 0.277 0.494 0.853 

1.088 0.401 0.601 0.974 

1.100 0.299 0.547 0.906 

1.057 0.317 0.530 0.866 

1.305 0.281 0.565 1.057 

1.220 0.315 0.582 1.109 

0.945 0.355 0.521 0.853 

1.041 0.270 0.472 0.807 

1.100 0.327 0.549 0.907 

1.023 0.336 0.538 0.879 

1.415 0.380 0.620 1.125 

1.090 0.291 0.502 0.889 

0.910 0.310 0.520 0.920 

0.913 0.219 0.420 0.657 

0.970 0.260 0.464 0.804 

1.079 0.265 0.469 0.751 

1.020 0.290 0.510 0.870 

1.135 0.275 0.493 0.889 

1.051 0.285 0.490 0.809 

1.240 0.310 0.490 0.870 

0.970 0.250 0.440 0.730 

1.070 0.287 0.522 0.848 

1.090 0.300 0.550 0.880 

0.890 0.220 0.410 0.690 

1.111 0.294 0.523 0.764 

1.030 0.480 0.510 0.950 

0.332 0.621 1.368 

1.220 0.316 0.568 0.962 

1.269 0.357 0.621 1.088 

1.075 0.323 0.509 0.961 

1.260 0.370 0.600 1.030 

0.950 0.290 0.440 0.760 

1.039 0.295 0.516 0.903 

199 200 201 202 

0.081 0.111 0.195 0.256 

nq 0.073 0.108 0.227 

nq 0.134 0.219 0.282 

nq 0.091 0.181 0.283 

0.031 0.087 0.155 0.244 

0.027 0.099 0.180 0.263 

0.012 0.081 0.173 0.283 

0.066 0.108 0.147 0.184 

0.070 0.120 0.190 0.270 

199 200 201 202 

6.97 6.95 9.98 17.8 

6.60 6.20 9.10 16.1 

7.69 7.22 10.39 18.0 

7.40 7.08 10.25 18.1 

7.19 7.25 10.17 17.8 

7.43 7.14 10.07 17.3 

7.62 7.57 10.48 18.3 

6.51 6.26 9.02 16.4 

9.05 9.05 11.20 21.5 

7.00 6.60 9.20 17.5 

9.76 9.71 12.24 19.5 

6.45 5.94 8.92 16.3 

7.75 7.49 10.05 17.1 

5.55 4.61 9.65 15.3 

7.22 6.71 9.54 16.7 

7.21 7.07 9.81 17.0 

7.92 7.97 10.50 19.0 

7.09 7.20 9.86 17.9 

7.69 7.56 10.33 18.7 

7.72 7.43 10.90 20.0 

6.81 7.11 9.52 17.1 

6.32 4.83 7.92 13.0 

7.30 7.20 10.10 22.3 

6.75 6.31 9.35 17.0 

7.73 7.29 12.13 18.8 

7.30 7.00 9.90 17.7 

7.29 6.98 9.90 17.0 

6.38 6.13 9.00 15.8 

7.50 7.20 9.70 18.9 

7.25 7.17 10.29 18.6 

7.16 6.95 10.00 20.2 

7.50 7.30 10.30 20.1 

7.15 8.44 11.60 19.2 

6.96 6.63 10.63 15.6 

7.37 8.88 9.88 17.6 

7.77 11.40 19.1 

8.45 7.15 10.60 19.4 

7.87 7.55 10.70 19.0 

7.34 7.64 9.96 16.6 

6.11 5.74 6.69 15.5 

7.21 7.18 10.04 18.2 

7.17 7.03 9.93 17.1 

199 200 201 202 

2.21 1.67 2.21 3.41 

2.53 1.75 2.53 3.81 

2.56 1.82 2.57 4.05 

2.03 1.45 2.02 3.11 

2.53 1.75 2.49 3.80 

2.67 1.92 2.60 4.23 

2.55 1.99 2.54 3.66 

2.50 1.65 2.41 3.82 

2.35 1.64 2.31 3.73 

2.21 1.71 2.15 3.26 

2.05 1.44 2.05 3.27 

2.46 1.80 2.43 3.80 

2.18 1.47 2.27 3.33 

2.60 1.60 2.40 3.90 

2.18 1.43 2.07 3.55 

5.66 3.76 6.22 8.17 

2.61 1.98 2.63 3.91 

1.74 1.19 1.72 2.84 

199 200 201 202 

0.81 0.87 1.00 0.95 

n 39 40 40 40 

Min 0.890 0.219 0.410 0.657 

Mean 1.080 0.306 0.521 0.895 

Max 1.415 0.480 0.621 1.368 

SD 0.117 0.047 0.052 0.130 

CV 11 15 10 15 

6 9 9 9 

0.012 0.073 0.108 0.184 

0.048 0.100 0.172 0.255 

0.081 0.134 0.219 0.283 

0.028 0.020 0.032 0.033 

59 20 19 13 

41 42 42 42 18 18 18 18 

5.55 4.61 6.69 13.0 1.74 1.19 1.72 2.84 

7.29 7.11 10.03 17.9 2.53 1.78 2.53 3.87 

9.76 9.71 12.24 22.3 5.66 3.76 6.22 8.17 

0.73 0.94 0.98 1.7 0.82 0.54 0.95 1.13 

10 13 10 10 32 30 38 29 

1 1 1 1 

0.81 0.87 1.00 0.95 

NISTa 

NISTb 

1.080 0.303 0.539 0.923 

0.299 0.509 0.901 0.090 0.161 0.221 

6.90 6.82 9.39 17.2 

7.05 10.10 17.8 

2.11 1.43 2.04 3.25 

1.65 2.30 3.65 0.09 0.13 0.18 

Median 

eCV 

1.070 0.300 0.515 0.879 

7 9 7 11 

0.049 0.099 0.180 0.263 

66 18 12 11 

7.25 7.16 10.02 17.8 

6 7 6 9 

2.48 1.69 2.41 3.76 

10 16 11 10 

K2
 

All Lab Report Page 1 / 5 
Round Robin XXXII Laboratory Results 

Results in ug/mL 

Lab 

Total β-Carotene

199 200 201 

trans-β-Carotene Total cis-β-Carotene

202 

9-cis-β-Carotene

FSV-BA 0.615 0.266 0.705 1.29 

FSV-BD 

FSV-BE 0.578 0.239 0.624 1.21 

FSV-BF 0.571 0.319 0.587 1.23 

FSV-BH 0.594 0.223 0.654 1.25 

FSV-BI 0.591 0.244 0.614 1.10 

FSV-BJ 0.602 0.277 0.673 1.21 

FSV-BK 

FSV-BL 

FSV-BM 

FSV-BN 0.542 0.218 0.449 1.00 

FSV-BO 0.766 0.369 0.782 1.45 

FSV-BP 0.463 0.237 0.496 0.86 

FSV-BQ 0.661 0.328 0.399 1.45 

FSV-BT 0.524 0.246 0.598 1.21 

FSV-BX >0.540 >0.240 >0.575 >1.099 

FSV-BY 0.626 0.306 0.763 1.54 

FSV-BZ 0.470 0.298 0.609 0.95 

FSV-CA 

FSV-CB 0.595 0.226 0.594 1.14 

FSV-CH 0.604 0.249 0.667 1.41 

FSV-CK 0.706 0.278 0.749 1.44 

FSV-CL 0.363 0.136 0.356 0.73 

FSV-CM 

FSV-CO 0.611 0.269 0.670 1.28 

FSV-CQ 0.376 0.120 0.428 0.87 

FSV-CR 

FSV-CT 0.613 0.264 0.634 1.28 

FSV-CU 0.517 0.218 0.562 1.03 

FSV-CV 0.610 0.275 0.640 1.27 

FSV-CX 0.440 0.200 0.480 0.85 

FSV-CY 0.500 0.223 0.557 1.59 

FSV-DJ 

FSV-DK 

FSV-DL 0.468 0.193 0.558 0.92 

FSV-DS 0.666 0.440 0.742 1.33 

FSV-DU >0.320 >0.600 >1.060 

FSV-DX 0.556 0.239 0.633 1.24 

FSV-EA 0.839 0.353 0.885 1.69 

FSV-EC 0.596 0.258 0.654 1.42 

FSV-EK 0.680 0.260 0.540 1.15 

FSV-EX 0.560 0.180 0.590 1.15 

FSV-FD 0.585 0.241 0.656 1.24 

199 200 201 202 

0.574 0.251 0.662 1.22 

0.564 0.213 0.623 1.19 

0.485 0.196 0.415 0.90 

0.493 0.231 0.560 1.12 

0.240 0.575 1.10 

0.531 0.234 0.565 1.12 

0.480 0.211 0.532 0.98 

0.320 0.600 1.06 

199 

0.041 

0.030 

0.057 

0.032 

0.081 

0.037 

200 

0.015 

0.010 

0.022 

0.015 

0.035 

0.007 

201 

0.043 

0.031 

0.034 

0.038 

0.106 

0.030 

202 

0.075 

0.059 

0.098 

0.089 

0.163 

0.049 

199 200 201 202 

0.031 nq nq 0.049 

0.063 <0.014 0.057 0.120 

n 

Min 

Mean 

Max 

SD 

CV 

NISTa 

NISTb 

Median 

eCV 

32 

0.363 

0.578 

0.839 

0.100 

17 

32 

0.120 

0.256 

0.440 

0.063 

25 

0.520 0.240 

0.255 

0.593 

11 

0.248 

17 

32 

0.356 

0.611 

0.885 

0.114 

19 

0.624 

0.641 

0.619 

13 

32 

0.73 

1.21 

1.69 

0.23 

19 

1.05 

1.27 

1.23 

19 

6 8 8 8 

0.480 0.196 0.415 0.90 

0.521 0.237 0.566 1.08 

0.574 0.320 0.662 1.22 

0.041 0.038 0.073 0.10 

8 16 13 10 

0.448 0.209 0.558 0.98 

0.231 0.585 1.16 

0.512 0.232 0.570 1.11 

8 12 9 9 

6 

0.030 

0.046 

0.081 

0.019 

42 

0.072 

0.039 

30 

6 

0.007 

0.017 

0.035 

0.010 

58 

0.031 

0.024 

0.015 

59 

6 

0.030 

0.047 

0.106 

0.029 

62 

0.066 

0.056 

0.036 

23 

6 

0.049 

0.089 

0.163 

0.041 

46 

0.072 

0.110 

0.082 

35 

2 0 1 2 

0.031 0.049 

0.047 0.057 0.085 

0.063 0.120 

K3
 

All Lab Report Page 2 / 5 
Lab 

FSV-BA
 

FSV-BD
 

FSV-BE
 

FSV-BF
 

FSV-BH
 

FSV-BI
 

FSV-BJ
 

FSV-BK
 

FSV-BL
 

FSV-BM
 

FSV-BN
 

FSV-BO
 

FSV-BP
 

FSV-BQ
 

FSV-BT
 

FSV-BX
 

FSV-BY
 

FSV-BZ
 

FSV-CA
 

FSV-CB
 

FSV-CH
 

FSV-CK
 

FSV-CL
 

FSV-CM 

FSV-CO 

FSV-CQ 

FSV-CR 

FSV-CT 

FSV-CU 

FSV-CV 

FSV-CX 

FSV-CY 

FSV-DJ 

FSV-DK 

FSV-DL 

FSV-DS 

FSV-DU 

FSV-DX 

FSV-EA 

FSV-EC 

FSV-EK 

FSV-EX 

FSV-FD 

n 

Min 

Mean 

Max 

SD 

CV 

NISTa 

NISTb 

Median 

eCV 

Total α-Carotene

199 200 201 202 

0.020 0.023 0.038 0.047 

0.018 0.029 0.038 0.043 

0.029 0.033 0.057 0.076 

0.017 0.017 0.032 0.044 

0.014 0.016 0.027 0.035 

0.022 0.030 0.040 0.053 

0.015 0.016 0.026 0.037 

0.010 0.017 0.024 0.032 

0.017 0.017 0.023 0.026 

0.019 0.020 0.030 0.039 

0.003 0.011 0.014 0.015 

0.018 0.020 0.044 0.068 

0.042 0.032 0.059 0.053 

0.015 0.014 0.024 0.032 

0.008 0.008 0.010 0.020 

0.024 0.023 0.038 0.055 

0.010 0.011 0.016 0.020 

0.034 0.035 0.052 0.076 

0.010 0.020 0.020 0.030 

0.015 0.016 0.032 0.039 

nq 0.019 0.027 nq 

0.032 0.033 0.048 0.066 

21 22 22 21 

0.003 0.008 0.010 0.015 

0.019 0.021 0.033 0.043 

0.042 0.035 0.059 0.076 

0.009 0.008 0.013 0.018 

50 38 41 42 

0.024 0.019 0.037 0.039 

0.025 0.043 0.062 

0.017 0.020 0.031 0.039 

44 27 37 49 

Round Robin XXXII Laboratory Results 

Results in ug/mL 

Total Lycopene trans-Lycopene Total β-Cryptoxanthin

199 200 201 202 

0.59 0.251 0.310 0.391 

0.61 0.165 0.300 0.322 

0.52 0.152 0.240 0.250 

0.55 0.177 0.288 0.277 

0.71 0.250 0.302 0.358 

0.50 0.171 0.252 0.291 

0.65 0.201 0.258 0.360 

0.48 0.180 0.265 0.305 

0.87 0.293 0.389 0.337 

0.63 0.183 0.286 0.327 

0.38 0.175 0.229 0.243 

0.42 0.108 0.180 0.223 

0.63 0.170 0.270 0.314 

0.77 0.219 0.192 0.433 

0.59 0.167 0.266 0.313 

0.45 0.156 0.240 0.250 

0.56 0.185 0.285 0.300 

0.66 0.210 0.320 0.330 

0.46 0.134 0.247 0.226 

0.46 0.184 0.308 0.353 

0.76 0.240 0.326 0.435 

0.35 0.110 0.180 0.200 

199 200 201 202 

0.35 0.10 0.17 0.18 

199 200 201 202 

0.067 0.041 0.054 0.050 

0.078 0.040 0.055 0.052 

0.062 0.028 0.040 0.038 

0.023 0.020 0.024 0.022 

0.109 0.102 0.109 0.110 

0.154 0.081 0.105 0.095 

0.061 0.032 0.044 0.043 

0.075 0.049 0.058 0.047 

0.075 0.042 0.051 0.053 

0.056 0.026 0.037 0.038 

0.066 0.030 0.043 0.047 

0.164 0.133 0.143 0.138 

0.084 0.058 0.063 0.063 

0.050 0.030 0.040 0.030 

0.058 0.041 0.037 0.045 

0.084 0.048 0.059 0.063 

22 22 22 22 

0.35 0.108 0.180 0.200 

0.57 0.185 0.270 0.311 

0.87 0.293 0.389 0.435 

0.13 0.045 0.050 0.064 

23 24 19 21 

1 1 1 1 

0.35 0.10 0.17 0.18 

16 16 16 16 

0.023 0.020 0.024 0.022 

0.079 0.050 0.060 0.058 

0.164 0.133 0.143 0.138 

0.036 0.031 0.032 0.031 

46 61 53 53 

0.235 0.359 0.406 

0.57 0.179 0.268 0.314 

23 19 17 20 

0.09 0.15 0.16 

K4

0.024 0.032 0.033 

0.071 0.041 0.053 0.049 

27 40 32 32 

Total Lutein 

199 200 201 202 

0.070 0.055 0.062 0.051 

0.070 0.054 0.057 0.035 

0.040 0.022 0.026 0.016 

0.090 0.064 0.068 0.036 

0.073 0.052 0.056 0.031 

0.096 0.067 0.062 0.034 

0.072 0.061 0.064 0.036 

0.135 0.129 0.102 0.058 

0.110 0.080 0.090 0.050 

0.099 0.067 0.072 0.059 

0.130 0.090 0.090 0.810 

11 11 11 11 

0.040 0.022 0.026 0.016 

0.090 0.067 0.068 0.111 

0.135 0.129 0.102 0.810 

0.028 0.027 0.021 0.232 

32 40 30 210 

0.058 0.063 0.043 

0.090 0.064 0.064 0.036 

33 23 19 58 

All Lab Report Page 3 / 5 
Round Robin XXXII Laboratory Results 

Results in ug/mL 

Total Zeaxanthin Total Lutein&Zeaxanthin 

Lab 199 200 201 202 199 200 201 202 

FSV-BA
 

FSV-BD
 

FSV-BE
 

FSV-BF
 

FSV-BH
 

FSV-BI
 

FSV-BJ
 

FSV-BK
 

FSV-BL
 

FSV-BM
 

FSV-BN
 

FSV-BO
 

FSV-BP
 

FSV-BQ
 

FSV-BT
 

FSV-BX
 

FSV-BY
 

FSV-BZ
 

FSV-CA
 

FSV-CB
 

FSV-CH
 

FSV-CK
 

FSV-CL
 

FSV-CM 

FSV-CO 

FSV-CQ 

FSV-CR 

FSV-CT 

FSV-CU 

FSV-CV 

FSV-CX 

FSV-CY 

FSV-DJ 

FSV-DK 

FSV-DL 

FSV-DS 

FSV-DU 

FSV-DX 

FSV-EA 

FSV-EC 

FSV-EK 

FSV-EX 

FSV-FD 

n 

Min 

Mean 

Max 

SD 

CV 

NISTa 

NISTb 

Median 

eCV 

0.126 0.101 0.100 0.054 

0.025 nq nq nq 0.095 

0.030 0.015 0.018 0.010 0.102 0.071 0.080 0.045 

Term 

n 

0.027 0.014 0.070 0.004 0.067 0.036 0.096 0.020 Min 

0.181 0.115 0.147 0.087 Mean 

Max 

SD

0.025 0.018 0.027 0.013 0.220 0.129 0.164 0.114 CV 

0.043 0.023 0.029 0.015 0.116 0.075 0.085 0.046 

0.038 0.022 0.023 0.031 0.134 0.089 0.085 0.065 Median 

eCV 

eSD 

0.155 0.113 0.125 0.078 

nq 

0.119 0.090 0.094 0.058

0.127 0.097 0.112 0.064 <x 

0.087 0.059 0.056 0.041 0.222 0.187 0.158 0.098 italics 

Analytes Reported By One Laboratory Only
 

Values in μg/mL
 

Analyte Code 199 200 201 202 

13-cis-β-Carotene FSV-BN 0.04 0.02 0.03 0.07 

Total Carotenoids FSV-BT 1.45 0.69 1.21 1.80 

trans-α-Carotene NISTb 0.02 0.03 0.04 

Definition

 Number quantitative values reported

 Minimum value reported

 Mean of values reported

 Maximum value reported

 Standard deviation of values reported 

 Coefficient of variation, 100*SD/Mean 

 Median of values reported

 Robust estimate of CV, 100*eSD/Median

 Robust estimate of standard deviation

 Not quantitatively determined, i.e., reported as

 "0", 'trace', 'not determined, etc. 

 Concentration at or below the limit of

 quantification (LOQ) x. 

 Calculated from reported values

7 6 6 6 

0.025 0.014 0.018 0.004 

0.039 0.025 0.037 0.019 

0.087 0.059 0.070 0.041 

0.022 0.017 0.021 0.014 

56 67 56 74 

0.097 0.078 0.097 0.045 

The original report estimated eSD and eCV from the 

interquartile range (IQR). 

13 

0.067 

0.135 

0.222 

0.047 

35 

12 

0.036 

0.098 

0.187 

0.037 

38 

12 

0.080 

0.112 

0.164 

0.030 

26 

12 

0.020 

0.065 

0.114 

0.026 

41 

0.031 0.042 0.032 0.089 0.105 0.075 

0.030 0.020 0.028 0.014 0.126 0.094 0.099 0.061 

25 28 40 74 34 31 20 39 

K5
 

All Lab Report Page 4 / 5 
Round Robin XXXII Laboratory Report
 

Interlaboratory Measurement Comparability Summary
 

Lab 

FSV-BA
 

FSV-BD
 

FSV-BE
 

FSV-BG
 

FSV-BH
 

FSV-BI
 

FSV-BJ
 

FSV-BK
 

FSV-BM
 

FSV-BN
 

FSV-BO
 

FSV-BP
 

FSV-BQ
 

FSV-BR
 

FSV-BS
 

FSV-BT
 

FSV-BU
 

FSV-BV
 

FSV-BX
 

FSV-BY
 

FSV-CA
 

FSV-CB
 

FSV-CD
 

FSV-CH
 

FSV-CJ
 

FSV-CK
 

FSV-CL
 

FSV-CM
 

FSV-CN
 

FSV-CP
 

FSV-CR
 

FSV-CT
 

FSV-CU
 

FSV-CV
 

FSV-CX
 

FSV-CY
 

FSV-DA
 

FSV-DB
 

FSV-DJ
 

FSV-DK
 

FSV-DL
 

FSV-DM
 

FSV-DP
 

R aT gT bC tbC 

1 1 2 2 2 

1 2 

2 2 1 1 

1 1 1 2 

3 1 2 1 1 

1 1 1 1 

1 1 2 1 

1 2 

4 4 

1 2 

1 4 2 2 3 

3 3 3 

3 2 2 

3 4 3 

2 1 1 2 1 

1 1

2 1 1 2

2 2 2

2 1

4 1 1 

1 2 2 1 

3 2 1 2 

3 4 4 

3

2 2 1 1 

2 4 4 

1 1 

1 1 2 1

1 2 2 2 

3 1 1 1 

2 1 2 3 

1 2 2 

1 2 

3 3 

2 2 4 2 

4 4 4 

4 3 2 3 

2 3 1 

3 2 2 4 

1 1 1 

3 4 3 2 

2 1 2 

1 1 1 

Label 

Lab

R 

aT 

gT 

bC 

tbC 

n 

Definition

 laboratory number 

 "Standard Score" for Retinol 

 "Standard Score" for α-Tocopherol

 "Standard Score" for γ-Tocopherol

 "Standard Score" for Total β-Carotene

 "Standard Score" for trans-β-Carotene

 number of laboratories providing data for this analyte 

"Standard Score" 

Given that our knowledge of the shape, location, and width of the measurement 

distributions is approximate and that a limited number of labs are involved, we 

summarize comparability with the following four-level "Standard Score" 

StS 

1 

2 

3 

4 

where: 

StV 

Median 

eSD 

t (1-α,n-1)

Definition 

 All StV within ±t (1-0.683,n-1) {i.e., ±1 SD} 

 All StV within ±t (1-0.954,n-1) {i.e., ±2 SD} 

 All StV within ±t (1-0.997,n-1) {i.e., ±3 SD} 

 At least one StV > ±t (1-0.997,n-1) {i.e., >3 SD} 

Standardized Value, the distance in standard deviation units your 

value is from the "true" concentration: 

 StV = (your value - Median) / eSD 

Median of values reported 

Robust estimate of standard deviation 

 Two-tailed Student's t for coverage of ±1, ±2, and ±3 eSD about 

 Median, assuming a normal population of size n 

K6
 

All Lab Report Page 5 / 5 
 

Appendix H. Representative “Individualized Report” for RR32 

Each participant in RR32 received an “Individualized Report” reflecting their reported 

results. Each report included a detailed analysis of the results they reported for the 

following analytes: 

• Retinol 

• Retinyl Palmitate 

• α-Tocopherol 

• γ-Tocopherol 

• Total β-Carotene 

• trans-β-Carotene 

• Total α-Carotene 

• Lutein 

• β-Cryptoxanthin 

• Zeaxanthin 

• Lycopene 

• Lutein & Zeaxanthin 

The following eight pages are the “Individualized Report” for the analytes evaluated by 

participant FSV-NIST1 (listed as FSV-NISTa in the “All Lab Report”). 

L1
 
11n194 

Individualized Round Robin XXXII Report to: NISTl 

Your Data, Inter-laboratory Medians, and %Differences 

Serum 199 Serum 200 Serum 201 Serum 202 

Analyte You Med %L\ n I You Med %L\ n II You Med %L\ n II You Med %L\ n I 

Retinol 1.08 1.06 2 37 0.30 0.30 1 37 0.54 0.51 5 37 0.92 0.87 6 37 

a-Tocopherol 6.90 7.22 -4 39 6.82 7.14 -4 39 9.39 9.98 -6 39 17.17 17.70 -3 39 

g-Tocopherol 2.11 2.50 -15 17 1.43 1.71 -16 17 2.04 2.41 -15 17 3.25 3.80 -14 17 

Total b-Carotene .520 .588 -12 30 .240 .245 -2 30 .624 .612 2 30 1.050 1.219 -14 30 

trans-b-Carotene .448 .535 -16 8 .209 .232 -10 8 .558 .570 -2 8 .978 1.117 -12 8 

Total a-Carotene .024 .018 37 20 .019 .020 -5 21 .037 .032 16 21 .039 .041 -5 20 

You : Your reported values for the listed analytes (micrograms/milliliter) 

Med : The median of the values reported by all participating laboratories (excluding NIST.) 

: The percent difference between your value and the median (reported for main analytes only.) 

n : The number of laboratories reporting quantitative values for this analyte in this serum (excluding NIST.) 

Please check our recorded values against your records. 

Fax any corrections to: (301) 926-8671, c/o Donna Sirk, 222/Bl56, NIST, Gaithersburg, MD 20899 

.• 1ge I/ K 

L2
 
50 

i:: 

:.a 25 

0 x 

x 

i:: I 

·- I "'O 

0 I 

0 

I 

..0 

d 

* 8 

..-4 

<l -25 

-50 

11n194 

Individualized Round Robin XXXII Report to: NISTl 

Retinol, in Round Robin XXIII - XXXII 

x 

x x 

x x x v 

x x x v I 

I x v I I 

v v I I "'"'"' I 

1111 1111 lilt 11111 11111 11111 11111 Jill 1111 1222 

5 5 5 5 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 8 8 8 8 8 8 8 8 8 9 9 9 9 9 9 9 9 9 9 0 0 0 

5 6 7 9 0 I 2 3 4 5 6 7 8 9 0 I 2 3 4 5 6 7 I 2 3 4 5 6 7 8 9 0 I 2 3 4 5 6 7 8 9 0 I 2 

X32_NISTl_R1·· ·•o 21 8 

L3
 
50 

s::: 

"" ..... 25 - "'O 

0 

,_ 

s::: 

1l 

"" ..... "'O 

0 

::E 0 

I 

.J::J 

"" .,_. 

* 8 

<I -25 

-50 _J 

11n/94 

Individualized Round Robin XXXII Report to: NISTl 

Tocopherol, %.!\in Round Robin XXIII - XXXII 

1 1 1 1 1 1 1 1 1 1 1 1 

5 5 5 5 6 6 6 6 6 6 6 6 

5 6 7 9 0 I 2 3 4 5 6 7 

• g-Tocopherol Ill a-Tocopherol 

1 1 I 1 1 1 1 1 1 1 1 1 1 1 1 

6 6 7 7 7 7 7 7 7 7 8 8 8 8 8 

8 9 0 I 2 3 4 5 6 7 1 2 3 4 5 

Serum 

,0 I 

I I I I I 

8 8 8 8 9 

6 7 8 9 0 

111r1 

I 1 1 1 1 I I I I 2 2 2 

9 9 9 9 9 9 9 9 9 0 0 0 

1 2 3 4 5 6 7 8 9 0 1 2 

X32_NISTl_Rc··- •c 3 / 8 

L4
 
50 

s:: 

(':S 

:-a 25 

G) 

r: 

,-.... 

s:: 

(':S 

..... 

'O 

G) 

0 

I 

.0 

(':S 

I '-" * 0 

0 

..--4 

<l -25 

-50 

11n194 

Individualized Round Robin XXXII Report to: NISTl 

b-Carotene, %1\ in Round Robin XXIII - XXXII 

x x x x 

I v 

v I 

• ..- - I 

• All trans-b-Carotene llitfil Total b-Carotene 

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I I 1 I I I 1 I I I 

5 5 5 5 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 8 8 8 8 8 8 8 8 8 9 9 9 9 9 9 9 9 9 5 6 7 9 0 I 2 3 4 5 6 7 8 9 0 I 2 3 4 5 6 7 I 2 3 4 5 6 7 8 9 0 I 2 3 4 5 6 7 8 

Serum 

[ij• 

1 2 2 

9 0 0 9 0 I 

X32_NISTl_R,. •< 4 / 8 

L5
 
11n194 

-±20% 

±50% 

-±20% 

- - ±50% 

Individualized Round Robin XXXII Report to: NISTl 

Inter-laboratory Median Vs Laboratory NISTl Values 

Retinol 

a-Tocopherol_, -

.&.Total 

®trans 

-±20% 

±50% 

-±20% 

±50% 

b-Carotene 

g-Tocopherol , , , 

Legend 

Shaded Symbols: Round Robin XXIII-XXXI 

Black Symbols: Round Robin XXXII 

Ordinate: Median analyte concentration 

Abscissa: Your reported concentration 

Interpretation 

Adequately intercomparible data are within the 

±20% lines. If you have data scattered outside 

the ±50% lines, your measurement system is 

not consistent with that of most participating 

laboratories. If your data are systematically 

higher or lower than the median, your system may be consistent but your results are biased. 

If your data show increased scatter at low 

concentrations, your "limit of quantification" 

may not be what you think it is. 

If there are one or two "wild" outliers, they 

might be calculation or transcription errors. 

We would appreciate hearing from you about 

any such problems. 

X32

_NISTl_Rcr '"C 51 K 

L6
 
Individualized Round Robin XXXII Report to: NISTl 

(Provisional) Performance Summary 

XXIII 

XXIV 

xxv 

XXVI 

XXVII 

XXVIII 

XXIX 

xxx 

XXXI 

XXXII 

Ret 

ll1A 

-IO 

-5 

2 

1 

-8 

-1 

-I 

0 

4 

v/l 

4 4 

5 

3 6 3 

6 

2 2 

a Toe gToc Total trans 

ll1A v/l ll1A v/l ll1A v/l ll1A 

-6 4 0 4 7 6 

-2 4 -1 16 -5 16 

0 4 -6 8 7 IO 1 

-1 3 2 3 -15 7 -16 

4 1 6 4 2 10 -10 

-2 I -14 4 9 8 7 

-5 3 -17 5 -6 4 4 

-6 2 -4 5 6 3 -8 

-4 I -15 1 -6 8 -IO 

(Provisional) Performance Criteria 

In past Round Robins, the absolute value of the %/l of each measurement 

was evaluated 0-5%: Exceptional 

6-IO%: Acceptable 

11-20%: Marginal 

>20%: Poor 

lln/94 

v/l 

9 9 

6 

7 

9 

IO 

6 

Ret: Retinol 

aToc: a-Tocopherol 

gToc: g-Tocopherol 

Total: Total b-Carotene 

trans: All trans-b-Carotene 

Legend 

lllA: Mean difference, the average %/l for all sera of a given RR, where 

%/l = 100(Your value - median) I median 

v/l: Difference variability, one standard deviation of %/l for all sera of a RR 

Rational 

There are no definitive methods for fat-soluble vitamin-related analytes in serum. 

It's difficult to judge your absolute performance. However, you can compare your 

measurements to the group's consensus values - and to ours here at NIST. There 

are two kindred aspects to this relative comparison: accuracy and precision. 

Accuracy can be estimated as average %/l [JOO(your value - median)/median] 

over all sera of a given Round Robin. Precision can be estimated as one 

standard deviation of the %/l over all sera of a given Round Robin. 

It's best to be accurate and precise (small lllA, small v/l.) In some sense, good 

precision (small v/l) with poor accuracy (large lllA) is better than the converse: 

such values are internally consistent and may be relatable to the group's values. 

Poor precision (large v/l) suggests that your measurement system is qualitatively 

different from that used by NIST and the majority of participating laboratories. 

X32_NISTl_Rcr- " •gc 61 

L7
 
Individualized Round Robin XXXII Report to: NISTl 

Comparisons to Known Relationships 

0 

c:: 

..... 

...... 

0 

i:-=•--i 

L_-• -=3 

1:---:1 

l 

Ej 

8 

0 

.Q t [_---=- -3 0.. l _ . - 0 

(.) 

0 

- tij 

8 

..8 

g. (.) ·-

0 

EJ-

• • b.O 

B 

• 

t3 

• 

Ei=l 

r-=1 

-

.

-

0 

c:: 

-] 2 j I • I 

-· • 0 - -- - a 

L::- I 1:91 • 

u I •-

,.0 

-

E· J 

o · 

c:: 

0 

0 a. 

u 

I 

-9 

en 

m 

!:q 

L9 -J 

1e1 

I 

''i' 

Feb-94 Aug:94 ---200----201-- 202 - Feb-94- -- I ---ZOO --- 201 - 202 -- Feb-94 - Aug-:.'94 - 200 2or -- 202-

11n194 """, X32_NISTl_Rer -·-··e 71 M 

L8
 
Individualized Round Robin XXXII Report to: NISTl 

Comparisons to Known Relationships (Continued) 

lJ 

c: 

·-'5 

§ 

Cl) 

;.< 

c: 

o . 

._ Cl) 

-

.

-

Fl 

I 

On r-J 

I 

- .0 

cU 

Ci! 

...... 

0 

E-< 

r- ., - I --,- ·r - r 

c: 

·-

B l:d 

D 

[1 

o 

f I 1 I 

Cl) 

I 1 I I 

c: 

8. 

0 

0 

;;:... 

....l 

r -

u r 111 r 

1 

r 1 

Qd 

c: 

·-B 

Feb-94-Aug:94 ---2 00-----201- 202 . Feb-94 Aug-94 - ' ----ZOO - 201 -·202- Fcl>-94 ·A.ug:94- - ' -- 200 -- 2m-·202 

11n/94 X32_NISTl _R,· 8 / M 

L9
 
 

Appendix M. Shipping Package Inserts for RR05 

The following two items were included in each package shipped to a RR05 participant: 

• Cover letter 

• Report of Analysis datasheet 

The cover letter and datasheets were enclosed in a sealed waterproof bag along with the 

samples themselves. 

M1
 
 

 

 

 

 

 

U N I TE D ST A T ES D EP A R TM E N T O F C O M M ER C E 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-0001 

April 14, 1994 

Dr. Margolis sent individual letters to invited study participants. The “~1” and “~2” 1~ 

were mail-merge commands for inserting a participant’s name and address. This 

page was prepared from the original working draft. 2~ 

Thank you for agreeing to measure the ascorbic acid in the accompanying samples. The samples 

which are in sealed ampoules were prepared by adding equal volumes of spiked human serum to 

10% metaphosphoric acid (MPA). All samples have been stored at -70 °C and should be kept at 

this temperature. I have checked them for stability and the ascorbic acid appears sufficiently 

stable. 

You should find four ampoules in the shipping container. Each ampoule contains between 0.2 

and 0.8 mg of ascorbic acid/dL of serum and each ampoule should be analyzed in duplicate by 

the method(s) used in your laboratory (preferably one measuring total ascorbic acid). 

The samples should be defrosted by warming at 20 °C for not more than 10 min otherwise some 

oxidation of ascorbic acid may occur. 

A report form is attached and I would appreciate it if you would make your measurements and 

return your results to me by May 31, 1994. Your results will be kept confidential. We will use 

these results in a study to demonstrate the comparative accuracy and precision of the laboratories 

currently measuring ascorbic acid. However, values will not be assigned to individual labs. If 

you wish to FAX your results, the number is (301) 926-8671. If you have any questions, I can be 

reached at (301) 975-3137. 

Thank you for your assistance. 

Sincerely, 

Sam A. Margolis, Ph. D. 

Research Chemist 

Organic Analytical Research Division 

Chemical Science and Technology Laboratory 

M2 
 

 

 

 

REPORT OF ANALYSIS 

NAME: 

Name and mailing address were specified on sheet set to each participant 

ADDRESS: 

Telephone Number: 

FAX Number: 

SERUM 178, VIAL# 

RESULTS (μg/mL) 

REPLICATE 1 

REPLICATE 2 

________ μg/mL 

________ 

SERUM 178, VIAL# 

REPLICATE 1 

REPLICATE 2 

________ μg/mL 

________ 

SERUM 179, VIAL# 

REPLICATE 1 

REPLICATE 2 

________ μg/mL 

________ 

SERUM 179, VIAL# 

REPLICATE 1 

REPLICATE 2 

________ μg/mL 

________ 

M3
 
 

 

 

 

 

 

Appendix N. Final Report for RR05 

The following eight pages are the final report for RR05 as provided to all participants. 

This report contains: 

•	 Cover letter and analysis of results. 

•	 Table 1 “Results of the Round Robin Measurement of Ascorbic Acid in Human 

Plasma”. 

•	 Table 2 “NIST Results for the Measurement of AA in Human Plasma”. 

•	 Figure 1 “Box Plot of the Round Robin Results” 

•	 Figure 2 “Distribution of the Round Robin Results for Lot 178” 

•	 Figure 3 “Distribution of the Round Robin Results for Lot 179” 

•	 A page intended to facilitate the participants’ return of comments 

A number of the results reported in the Tables were later revised to correct for 

miscommunication of the reporting units. Since the listed results do not necessarily 

represent measurement performance, the Lab identifiers used by Dr. Margolis have been 

redacted from these Tables rather than re-coded. The reporting unit confusion impacts 

some of the conclusions discussed in the cover letter. However, the results discussed in 

the Dr. Margolis’s text have not been updated or corrected. 

The “All Lab Report” in Appendix O lists the corrected results and provides more 

extensive statistical summaries. 

N1
 
 

 

 

 

U N I TE D ST A T ES D EP A R TM E N T O F C O M M ER C E 

National Institute of Standards and Technology 

Gaithersburg, Maryland 20899-0001 

August 1, 1994 The letter as distributed to participants has been lost. This 

version has been prepared from an extant draft. 

Dear Colleague: 

This report describes both the overall-group and your laboratory's performance in Round 

Robin V for the measurement of ascorbic acid in human plasma. The study involve the duplicate 

analysis of four samples (two each from lots 178 and 179). Specifically, your package contains 

tabular presentations of all data submitted for ascorbic acid for Round Robin V. Your results are 

designated "Data Set_ #" in the tables and figures. 

Table 1 provides a summary of the data submitted by sixteen Laboratories (the NIST data were 

not included in the statistical analysis). Two laboratories submitted three sets of measurements, 

each done by a different method. As shown in Table 1, the percent Relative Standard Deviation 

(RSD) for both lots ranged from 17.9 to 26.8. The intralaboratory %RSD ranged from 0.7 to 8.5 

except for one measurement with a %RSD of 15.7 indicating that the major source of variation 

was the interlaboratory variation. The box plot in Figure 1 is a graphic summary of the results. 

The highest and lowest 10 % of the measurements for each lot are plotted as small solid circles, 

the two simple lines each span the next 15 % intervals and the center box contains the values 

from ten data sets. The NIST mean value for ascorbic acid (AA) + dehydro-AA are represented 

by a circle with a T inside and the NIST mean for reduced AA is represented by an R inside a 

circle. The horizontal line in the 50% boxes represents the median interlaboratory values which 

are slightly below the NIST values and the X represents the mean which is essentially identical 

to the NIST values. Finaly, the results of the previous round robin for lot 178 are compared to 

the results of this round robin and show a similar distribution of results. 

Figures 2 and 3 are plots of the distribution of the data points submitted by each laboratory for 

each sample lot. From these plots and data in Table 1, it is apparent that the results obtained 

with the dinitrophenylhydrazine (DNPH) method (data sets 2 to 4), except for data set 3 lot 179, 

fall into a group of values which are higher than the NIST mean by approximately 10 to 25 %. 

Two sets of LC data (sets 6 and 7) which were high were reported by the same laboratory that 

made measurements by the DNPH method. The majority of the sets of data obtained by LC 

methods are 5 to 15 % below the NIST mean. The high average mean of the DNPH 

measurements is not significant because of the wide distribution of values but it is consistent 

with previous round robins and suggest that the DNPH method may be positively biased. The 

basis of the distribution of the majority of the LC measurements below the NIST mean requires 

further evaluation along with the large variation in the results (%RSD = 18 to 26 %). The 

observation that all of the gravimetrically added AA was accounted for (Table 2) also supports 

the need to continue these round robins in order to reduce the measurement variation. 

N2 
 

 

If you have any questions concerning Round Robin V please indicate it on the enclose sheet and 

return it to us via mail (Donna Sirk, NIST, Chemistry B156, Gaithersburg, MD 20899) or FAX 

(301-926-8671), or contact me at 301-975-3137. 

The next set of samples, Round Robin VI, will be shipped around the August 15. 

Sincerely, 

Sam A. Margolis, Ph. D. 

Research Chemist 

Organic Analytical Research Division 

Chemical Science and Technology Laboratory 

Enclosures 

N3 
Table 1. Results of the Round Robin Measurement 0£ Ascorbic Acid 

in Human Plasma. 

Lab 

MEAN 

SD 

%RSD 

NIST 

AA + DHAA 

NIST 

AA 

Data Setb 

2 

6 

7 

12 

3 

5 

4 

1 

13 

14 

15 

11 

8 

9 

10 

18 

16 

19 

20 

21 

17 

Ascorbic Acid (mmol/L 

Method 

DNPH 

LC 

LC 

LC-EC 

DNPH 

ENZ 

DNPH 

DCIP 

LC-EC 

LC-EC 

LC-EC 

LC 

LC-EC+d 

LC-EC+p 

LC-EC-p 

LC 

LC-EC 

LC-EC 

LC-EC 

LC-EC 

Lot 

39.8 

33.2 

35.2 

20.1 

33.5 

26.7 

38.5 

30.5 

19.5 

28.4 

22.6 

20.1 

18.3 

14.9 

22.4 

21.8 

23.0 

30.9 

21.9 

22.8 

26.6 

7.1 

28.8 

178 

± 0.7 

± 2.8 

± 1.6 

± 2.2 

± 8.1 

± 2.0 

± 0.3 

± 2.0 

± 2.9 

± 0 

± 2.0 

± 0.8 

± 0.9 

± 0.6 

± 0.3 

± 0.2 

± 1.3 

± 0.4 

± 0.3 

± 1.9 

27 • 0 ± 0 • 5A 

10.2 ± 0.4A 

Plasma)" 

Lot 179 

53.8 

55.4 

58.8 

46.0 

43.2 

50.3 

56.2 

45.4 

43.9 

45.4 

45.1 

32.9 

36.2 

31.8 

39.8 

40.4 

38.0 

36.9 

40.3 

41.1 

44.1 

7.9 

17.9 

± 0.7 

± 1.2 

± 2.8 

± 7.2 

± 0 

± 3.6 

+ 1.0 

± 0.7 

± 3.6 

± 0 

± 2.9 

± 0.4 

± 0.3 

± 0.3 

+ 0 

±0.4 

±1.3 

± 3.2 

± 0 

± 0.6 

43. 5 ± 1. 5d 

12.1 ± 3.9d 

a Values represent the mean and SD of replicate measurements on 

two samples (total of 4 measurements). 

b The Data Set numbers correspond to those in the figures 2-4. 

c Values represent the mean and SD of replicate measurements on 

five samples (total of 10 measurements). 

N4
 
Table 2. NIST Results for the Measurement of AA in Human Plasma. 

Ascorbic Acid (mmol/L) 

without OTT with OTT supplemented 

Lot No. LMl (AA+DHAA) Amount 

Plasma 1 5.1 ± 1.1 ( 4 )" 11.5 ± 0.2 ( 4 ) 

178 10.2 ± 0.4 (4) 27.0 ± 0.5 ( 4 ) 

15.8 

179 12.1 ± 3.9 (10) 43.5 ± 1.5 (10) 

32.1 

180 15.1 ± 0.4 ( 4) 42.7 ± 0.3 ( 4 ) 

31.6 

Plasma 2 18.9 ± 6.5 (4) 52.2 ± l.6 ( 4) 

179B 67.2 ± 26.4 (5) 154.4 ± 1.1 (10) 

101.3 

a The value in parentheses is the number of measurements made. 

N5
 
Figure 1. Box Plot of the Round Robin Results 

Figure 2. Distribution of Round Robin Results for Lot 178 

Figure 3. Distribution of Round Robin Results for Lot 179 

Key for Figures 2 and 3: 

• First Vial; First Measurement 

+ Second Vial; First Measurement 

D First Vial: Second Measurement 

¢ Second Vial;Second Measurement 

N6
 
. . . 

x Average 

T NIST, total 

R NIST, reduced 

50 

,,-..... 

40 

~ JI. 

.........., 

'"O 

•....C 

(.) 30 

< 

(.) 

• ....c 

~ 

CV 

x 

0 

(.) 

t:f.l 20 

< .. 

10 

RR93 178 

• • 

--

• 

® 

RR94178 

• 

90% 

75% 

..___,,,.....____. 25% 

• • 

® 

10% 

RR94179 

N7
 
RR94ADAT.XLS 

Lot178 Lot179 

45.00 70.00 --

40.00 - 0 

0 g 60.00 • 

• • e • • 35.00 D • ~ ~ i:J. • - 0 0 

ii 50 00 _,_ • CIS • E • 0 • ' e . 0 

~ 30.00 • a • tll 

i • 1::1 • CIS 

a. 0 0 a. 0 

c 0 ...J ...J 0 

g 

- ~ 40.00 '-

~ 25.00 - 0 0 

0 0 

" e 

:: • B :s Q • - • • ~ Ll 8 - 

'O 8 • 'tJ if e ·o 20.00 El 0 

0 ·c:; 

<t • 0 ct 30.00 '-

tJ i:;J u 

:a • :e ... 15.00 0 0 0 

tJ 0 tJ 

Ill :e 20.00 - ct 

10.00 

10.00 

5.00 -

0.00 0.00 

0 2 4 6 8 10 12 14 16 18 20 22 0 2 4 6 8 10 12 14 1

Data Set Data Set 

Page 1 

N

8
title 

company 

address 

NCI QUALITY ASSURANCE PROGRAM 

N9
 
Appendix O. “All-Lab Report” for VC-RR05 

The following two pages a revised the “All-Lab Report” for RR05. This report contains 

the same information as originally provided to all participants, with the following 

exceptions: 

•	 the participant identifiers (Lab) have been altered to ensure confidentiality of 

identification codes assigned to laboratories.. 

•	 the order in which the participant results are listed has been altered. 

•	 results have been corrected and transformed to have units of μmol/L sample. 

•	 additional summary statistics have been included. 

•	 a Legend page has been added 

O1
 
Vitamin C Round Robin 5
 

O2

Lab Date Method 

VC-MA 30-Oct-94 HPLC-EC 

VC-MB 13-May-94 AO 

VC-MC 16-May-94 24DNPH 

VC-MD 16-May-94 HPLC-EC 

VC-ME 1-Jun-94 HPLC-EC 

VC-ML 31-May-94 HPLC-UV 

VC-MV 10-Jun-94 HPLC-EC 

VC-MX 24-May-94 HPLC-EC 

VC-MZ 26-May-94 HPLC-EC 

VC-NA 25-May-94 HPLC-EC 

VC-NB 1-Jun-94 HPLC-EC 

VC-NC 13-Jul-94 24DNPH 

VC-NG 6-Jun-94 HPLC-EC 

VC-NN 15-May-94 24DNPH 

VC-NP 13-May-94 HPLC-EC 

178, [TAA] μmol/L 

Mean S dup S rep S het S tot 

10.79 0.00 0.00 0.00 0.00 

13.63 0.80 0.57 0.70 0.70 

19.87 0.40 0.00 0.40 0.28 

17.10 1.10 0.76 0.96 0.95 

10.93 0.20 0.00 0.20 0.14 

15.47 0.20 0.14 

14.19 0.00 0.00 0.00 0.00 

11.21 0.20 0.00 0.20 0.14 

10.06 0.10 0.46 0.00 0.33 

11.55 0.45 0.56 0.22 0.51 

11.40 1.14 0.06 1.14 0.81 

19.22 0.18 0.22 0.09 0.20 

11.31 1.19 0.33 1.17 0.88 

16.75 1.61 0.40 1.58 1.17 

10.88 0.03 0.11 0.00 0.08 

179, [TAA] μmol/L 

Mean S dup S rep S het 

18.10 0.30 0.43 0.00 

25.12 0.20 2.22 0.00 

26.90 0.10 0.43 0.00 

28.53 1.20 1.08 0.93 

20.16 0.00 0.00 0.00 

18.45 1.61 

22.71 0.00 0.00 0.00 

19.87 0.00 0.00 0.00 

16.45 0.18 0.20 0.11 

18.98 0.66 0.39 0.60 

20.55 0.28 0.20 0.24 

27.86 0.45 0.60 0.16 

22.55 1.69 0.50 1.65 

21.57 0.00 0.00 0.00 

20.18 0.17 0.17 0.12 

N 15 15 

Min 10.06 0.00 0.00 0.00 0.00 16.45 0.00 0.00 0.00 

Median 11.55 0.20 0.17 0.21 0.28 20.55 0.20 0.29 0.06 

Max 19.87 1.61 0.76 1.58 1.17 28.53 1.69 2.22 1.65 

eSD 2.20 3.11 

eCV 19.0 15.2 

Revised "AllLabReport" 
Datasets 

Each participant typically reported two replicate measurements for each of two duplicate 

vials for each test sample. However, occasionally only one vial of each pair was 

evaluated or a single result was reported for each of the duplicate vials. 

Legend 

Lab	 Laboratory Code 

Date	 Date that the results were received at NIST 

Method Type of assay 

AO Ascorbate oxidase 

24DNPH 2,4-Dinitrophenylhydrazine 

EC Electrochemical detector 

HPLC Liquid chromatography 

OPD Orthophenlyenediamine 

UV Ultraviolet absorbance 

Mean Mean of duplicate means 

Sdup Standard deviation of duplicate means 

Srep Pooled standard deviation of replicates 

2 2 Shet	 Estimated sample heterogeneity, ටMAX൫0, Sdup − Shet൯

2 2 Stot	 Estimated standard deviation of the mean, ට൫Sdup + Srep൯⁄n, 

where n is the number of vials evaluated and is typically 2. 

N The number of participants 

Min Minimum value in the column 

Median Median value in the column 

Max Maximum value in the column 

eSD Adjusted median absolute deviation from the median (MADe) 

eCV Estimated coefficient of variation, 100*eSD/Median 

O3 
 

Appendix P. Shipping Package Inserts for RR06 

The following two items were included in each package shipped to a RR06 participant: 

• Cover letter 

• Report of Analysis datasheet 

The cover letter and datasheets were enclosed in a sealed waterproof bag along with the 

samples themselves. 

P1
 
P2
 
P3
 
 

REPORT OF ANALYSIS 

Name and mailing address specified on sheet set to each participant 

LAB NO.: Assigned code number
 

PHONE NO.:
 

FAX NO.:
 

Method of Analysis:
 

Date of Analysis:
 

RESULTS (μg/dL) 

SERUM 179, VIAL# 

REPLICATE 1 ________ mg/dL 

REPLICATE 2 ________ mg/dL 

SERUM 179, VIAL# 

REPLICATE 1 ________ mg/dL 

REPLICATE 2 ________ mg/dL 

SERUM 180, VIAL# 

REPLICATE 1 ________ mg/dL 

REPLICATE 2 ________ mg/dL 

SERUM 180, VIAL# 

REPLICATE 1 ________ mg/dL 

REPLICATE 2 ________ mg/dL 

P4
 
Appendix Q. “All-Lab Report” for VC-RR06 

The following two pages a revised the “All-Lab Report” for RR06. This report contains 

the same information as originally provided to all participants, with the following 

exceptions: 

•	 the participant identifiers (Lab) have been altered to ensure confidentiality of 

identification codes assigned to laboratories.. 

•	 the order in which the participant results are listed has been altered. 

•	 results have been corrected and transformed to have units of μmol/L sample. 

•	 additional summary statistics have been included. 

•	 a Legend page has been added 

Q1
 
Vitamin C Round Robin 6
 

Q2

Lab Date Method 

VC-MA 25-May-95 HPLC-EC 

VC-MB 19-Sep-94 AO 

VC-MC 22-Sep-94 24DNPH 

VC-MD 26-Sep-94 HPLC-EC 

VC-ME 22-Aug-94 HPLC-EC 

VC-MF 20-Sep-94 AutoAnal 

VC-ML 23-Sep-94 HPLC-UV 

VC-MV 23-Sep-94 HPLC-EC 

VC-MX 28-Sep-94 HPLC-EC 

VC-NA 28-Sep-94 HPLC-EC 

VC-NG 17-Oct-94 HPLC-EC 

179, [TAA] μmol/L 

Mean S dup S rep S het S tot 

19.66 0.10 0.14 0.00 0.12 

20.44 0.80 2.34 0.00 1.75 

27.39 0.20 0.63 0.00 0.47 

24.27 0.60 1.02 0.00 0.84 

21.08 0.10 0.14 0.00 0.12 

20.72 0.40 0.28 0.35 0.35 

29.04 2.37 2.37 

19.80 0.30 0.71 0.00 0.55 

19.59 0.80 0.00 0.80 0.57 

14.07 0.21 0.49 0.00 0.38 

22.78 0.30 0.14 0.28 0.24 

180, [TAA] μmol/L 

Mean S dup S rep S het 

19.16 0.20 0.40 0.00 

20.30 0.60 0.63 0.40 

26.40 0.80 0.40 0.75 

23.70 1.00 0.63 0.90 

20.16 0.60 0.45 0.51 

19.59 1.00 0.45 0.95 

19.99 1.53 0.80 1.42 

19.94 0.70 0.76 0.45 

18.81 0.50 0.14 0.49 

13.84 0.38 0.54 0.00 

22.00 0.00 0.20 0.00 

N 11 11 

Min 14.07 0.10 0.00 0.00 0.12 13.84 0.00 0.14 0.00 

Median 20.72 0.30 0.49 0.00 0.47 19.99 0.60 0.45 0.49 

Max 29.04 0.80 2.37 0.80 2.37 26.40 1.53 0.80 1.42 

eSD 1.68 1.22 

eCV 8.1 6.1 

Revised "AllLabReport" 
Datasets 

Each participant typically reported two replicate measurements for each of two duplicate 

vials for each test sample. However, occasionally only one vial of each pair was 

evaluated or a single result was reported for each of the duplicate vials. 

Legend 

Lab	 Laboratory Code 

Date	 Date that the results were received at NIST 

Method Type of assay 

AO Ascorbate oxidase 

24DNPH 2,4-Dinitrophenylhydrazine 

EC Electrochemical detector 

HPLC Liquid chromatography 

OPD Orthophenlyenediamine 

UV Ultraviolet absorbance 

Mean Mean of duplicate means 

Sdup Standard deviation of duplicate means 

Srep Pooled standard deviation of replicates 

2 2 Shet	 Estimated sample heterogeneity, ටMAX൫0, Sdup − Shet൯

2 2 Stot	 Estimated standard deviation of the mean, ට൫Sdup + Srep൯⁄n, 

where n is the number of vials evaluated and is typically 2. 

N The number of participants 

Min Minimum value in the column 

Median Median value in the column 

Max Maximum value in the column 

eSD Adjusted median absolute deviation from the median (MADe) 

eCV Estimated coefficient of variation, 100*eSD/Median 

Q3