USDA Food S3fety 3nd Inspection Service 

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Statistics and their role in evaluating an 

Establishments process control procedure 

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-Define Upper (UCL)and Lower Control Limits

(LCL)

-Baseline Studies (Regulatory Requirements)

-Define Statistical Process Control

-Basic Statistics terms

-Process Standards (Chart use)

-Microbiological Sampling

-Evaluating Sampling Data

Chapter 1- Statistical Control Definitions

A statistical control chart compares process performance data to computed “statistical control limits,”

drawn as limit lines on the chart. The process performance data usually consist of groups of measurements

(rational subgroups) from the regular sequence of production while preserving the order of the data.

Mean, median, mode, and statistical variance are all measures of

central tendency in statistics. In different ways they each tell us

what value in a data set is typical or representative of the data set.

Control limits are used to detect whether the variation in a

process we are observing is located within the expected

limits

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Statistical Process Control (SPC) 

Statistical Process Control (SPC) (cont.) 

. 

Upper and Lower Control Limits 

. 

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•

•

•

•

• Statistical process control initially involves

evaluating data to determine process capability

(the typical process performance level or baseline

level).

• Then checking subsequent data to see whether

they are consistent with this baseline level to

ensure the process is in control and variations are

The upper control limit (UCL) and lower control

limit (LCL), using SPC techniques, are boundaries

used to depict a stable process.

The UCL/LCL are calculated from the

establishment’s sampling data collected over time.

The UCL/LCL show the expected limits or normal

variation in the establishment’s process and are

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Statistical process control techniques are based on the principle

that every product is produced by a process. 

All processes are subject to variation, which can be monitored and

understood by statistical methods. 

A process that is in control is stable in terms of average level and

degree of variation, meaning it is predictable within limits. 

Control is maintained by detecting and eliminating root causes of

variation, that is, investigating causes of aberrant data points that

are not always present or those not affecting all product output. 

within normal and acceptable limits.

typically depicted on a control chart.

•

•

•

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Upper and Lower Control Limits 

Baseline Studies 

Statistical Process Control 

Some basic terms 

◄. 

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◄. 

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The sum of the values divided by the number of values

 3+5+6+8+10/5 = 32/5 = 6.4

The middle value of the dataset after ordering the dataset by

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• Many establishments may already have historical microbiological

sampling data that must be used to set the UCL and LCL. 

• If an establishment does not have historical sampling data, an

establishment may choose to use the values cited in the FSIS

baseline study, FSIS data resources, and FSIS guidance documents

for its own control limit values until it has sufficient data to conduct

its own SPC evaluation.

• Once the establishment collects sufficient data, FSIS baseline data

are no longer the sole data source, instead, the establishment must

use the data collected from its own sampling programs to conduct

SPC analysis. 

•

•

•

FSIS published in the Feb 17, 2005 Federal Register Notice (70 FR

8058), “Generic E. coli and Salmonella Baseline Results,” using

FSIS baseline study data. 

FSIS made these baseline results available for establishments to

supplement or support an establishment’s process control efforts

in tandem with SPC to help define when a process may be out of

control. 

The baseline data are for use as guidance to establishments and

do not replace the criteria and standards incorporated in the

regulations.

Mean (often called the Average)

•

• 3,5,6,8,10 5 values

Median

•

size

• Splits the data into two equally-sized groups

• 3,5,6,8,10 The median value is 6

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Statistical Process Control 

Some basic terms 

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Mode

• The value that occurs most frequently

In our data set 3,5,6,8,10, the mode would not be useful, as no value

appears more than the others.

• Let’s use this data set: 1, 2, 3, 5, 3, 7, 3, 6 3 is the value (mode) that occurs

most frequently.

Standard Deviation

•Measure of how much (spread) = (Control Limits) from the Mean

(average) exists in a dataset

• Here is the equ tandard Deviation (SD):

The following slides have an example

on how to calculate the SD.

Let’s use the sample set from previous calculations:

3,5,6,8,10

Step 1: Finding the mean

3+5+6+8+10/5 = 32/5 = 6.4

Step 2: Finding ( x-μ2)

Complete table below.

Data Point Distance Square of

from mean distance

from mean

3 3-6.4= -2.6 (-2.6)2 = 6.76

5 5-6.4=-1.4 (-1.4)2 = 1.96

6 6-6.4=-0.4 (-0.4)2 = 0.16

8 8-6.4=1.6 (1.6)2 = 2.56

10 10-6.4=3.6 (3.6)2 = 12.96

Step 3: Finding the sum of (x-μ)2

The symbol ∑ means "sum", so in this step we add

up the five values we found in Step 2.

6.76

6.76 +1.96 + 0.16 + 2.56 + 12.96 = 35.84

Step 4: In this step, we divide our result from Step

3 by the variable N, which is the number of data

points. (We have 5 data points)

35.84/5 = 7.168 (round to 7.17)

Step 5: Just take the square root of the answer

from Step 4 and we're done.

7.17 = 2.677 (round to 2.68)

The Standard Deviation from the mean of our

data is 2.68

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Statistical Process Control 

Some basic terms 

Statistical Process Control 

Some basic terms-Outliers 

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The Standard Deviation (SD) from the

mean of our data is 2.68

2.68 + 6.4 = 9.08 Upper Control Limit

Lower Control Limit

Mean

Mean

3+5+6+8+10/5 = 32/5 = 6.4

The Standard Deviation (SD) from

the mean of our data is 2.68

6.4 – 2.68 = 3.72

Here is the Statistical Control Chart using the SD to calculate the Upper

Control Limit (UCL) and the Lower Control Limit (LCL). Data inside those

limits would show process control!

Why do we need different measures?

The shape of the data can be skewed, could have outliers or

multiple modes.

The data on the right could be represented by either the mean, median or

mode, but the skew on the left dataset makes the median a better choice

An outlier is a data point in a data set that is distant from all

other observations. A data point that lies outside the overall

distribution of the dataset. Or in a layman term, we can say, 

an outlier is something that behaves differently from the

combination/collection of the data.

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Statistical Process Control 

Some basic terms-Outliers 

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Statistical Process Control 

Process Control Charts 

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However, the median and the mode of this set are still 5.

For this dataset, they would be better indicators of the

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Ex:

Suppose we had seven values of

5, 4, 5, 6, 7, 5, 17. Then, the mean is

(5+4+5+6+7+5+17)/7=49/7=7

central tendency than the mean.

Here, 17 is what we call an outlier

Chapter 2- Statistical Control Charts

Process control charts (Shewhart charts) are a

statistical process control tool used to study

how a process changes over time

-A control chart will have

a central line for the mean

an upper control limit (UCL) line

a lower control limit (LCL) line

-These values and lines are determined from

historical data.

You can draw conclusions about whether a

process is in control or not by comparing

current data to these lines.

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Statistical Process Control 

Process Control Charts-Using Excel Data 

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Statistical Process Control 

Data use 

Statistical Process Control 

Process Control Charts 

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•

•

•

• The control chart for System 1 depicts a pattern of test results that would be

seen in a well-controlled system.

A value of zero is not meaningful because in a microbiological

context it means it is below the limit of detection. 

Meaningful data will allow enumeration and enumeration

allows an establishment to plot these data on a process control

chart and monitor trends in its data and process over time. 

The more quantifiable microbiological data available to an

establishment, the better it can assess and subsequently control

variations in its process. 

• In a well-controlled system, the majority of test results will be clustered

around a central value.

• Note: Even in a well-controlled system, there is some frequency of isolated

results above the acceptable level

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Statistical Process Control 

Process Control Charts 

Statistical Process Control 

Process Control Charts 

Statistical Process Control 

Process Control Charts 

System2 

◄. 

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◄. 

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What are your thoughts regarding this System?

•

•

This chart depicts a loss of process control due to

excess variability. This is reflected in both an increased

number of results above the UCL, and an increase in

scatter points directly below it as well.

This chart suggests either a loss of control at a critical

control point or the existence of another critical control

point that had not been identified and controlled.

• This chart depicts a situation where a component of the process is losing its

effectiveness over time.

• The loss of process control is apparent by the upward trend in the data

points toward the UCL.

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Statistical Process Control 

Process Control Charts 

Statistical Process Control 

Corrective Actions 

◄. 

. 

◄. 

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• This chart depicts conditions where there is the existence of an intermittent

but reoccurring problem within the process. Note the repeating pattern of

the test results over time.

• An example of a situation where this pattern may be observed is the dripping

of condensation onto product as it travels down a conveyor belt.

• SPC principles require corrective action when sample results reach a

certain threshold, such as the UCL, which is often three standard

deviations above the running mean average.

• The establishment should consider trends in data within operations

and assess the root cause of these changes. 

• Randomness can be observed in the results, establishments may

consider if an outlier is observed by performing a root cause analysis.

• It is not advisable that an establishment raise its UCL in response to

upward trends or outliers in its sampling data since its UCL was

initially calculated based on its process being in control. 

Chapter 3- Sampling and Process Control

An establishment employee selects the samples for generic E. coli testing. The purpose

of generic E. coli testing is to verify the effectiveness of sanitation and process control in

slaughter establishments.

Performance Standards are FSIS's calculation of the national prevalence of

Salmonella on the indicated raw product based on data developed by FSIS in its

nationwide microbiological data collection programs and surveys.

Establishments that slaughter livestock and poultry are required under

the regulations to collect microbiological samples for indicator organisms

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Statistical Process Control 

Microbiological Sampling 

Performance Standards 

Statistical Process Control 

Microbiological Sampling 

◄. 

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Performance Standards are FSIS's calculation of the national

prevalence of Salmonella on the indicated raw product based

on data developed by FSIS in its nationwide microbiological

data collection programs and surveys. 

Copies of Reports on FSIS's Nationwide Microbiological Data

Collection Programs and Nationwide Microbiological Surveys

used in determining the prevalence of Salmonella on raw

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• Generic E. coli Testing for Livestock, (other than swine)

• Each official establishment that slaughters livestock, other than

swine, or ratites is required to test for Escherichia coli Biotype I, 

also known as “generic E. coli.”

• An establishment employee selects the samples for generic E. 

coli testing. The purpose of generic E. coli testing is to verify the

effectiveness of sanitation and process control in slaughter

establishments. 

• FSIS verifies that the establishment meets the regulatory

requirements for generic E. coli testing

•

•

products are available in the FSIS Docket Room.

• Fecal contamination is one of the principal sources of pathogenic organisms that

contaminate livestock carcasses. 

• Generic E. coli is an indicator of fecal contamination because it is common in the

intestinal tract of food animals. The intestinal tract is also the primary pathway for

contamination of carcasses with pathogens such as E. coli O157:H7, and

Salmonella. 

• Ongoing E. coli testing by livestock slaughter establishments helps them

determine whetherthe slaughter process is under control or whether carcasses

are being contaminated with feces. 

In other words, generic E. coli testing is a process control indicatorfor

fecal contamination.

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t 

Regulatory Requirements (cont.) 

. 

Microbiological Sampling 

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Chapter 4-Regulatory Requirements

• When an establishment is collecting microbiological

samples to meet the regulatory requirements, 

• How can the establishment use its test results to establish

and refine its control limits to evaluate its results and inform

process control?

• Establishments that slaughter livestock and poultry are

required under the regulations to collect microbiological

samples for indicator organisms, as specified: 

• 9 CFR 310.25 for cattle, sheep, goat; 

• 9 CFR 310.18(c) for swine; 

• 9 CFR 381.65(g) for poultry; and

• 9 CFR 381.94(a) for ratites

• An establishment must apply SPC principles to analyze trends in

its own sampling data over time to assess its process, with the

intention of optimizing its process control. SPC is required for

establishments that sponge cattle, sheep, and goat (9 CFR 310.25)

and for ratites (9 CFR 381.94(a)). 

• Part of this evaluation is to evaluate, at some frequency, whether

the defined control limits used are still appropriate, based on the

application of SPC principles to an analysis of the establishment’s

own sampling results. 

Sampling Requirements to Demonstrate Process

Control in Slaughter Operations

https://www.fsis.usda.gov/sites/default/files/media_file/2021-11/19_HQ-SamplingRequirements-Process-Control-Slaughter-Operations-03302020.pdf

• An establishment’s written sampling program must include a

description of how the establishment evaluates its own sampling

test results to determine if it is maintaining process control

sufficient to prevent contamination with enteric organisms.

• This evaluation involves the use of statistical process control (SPC)

techniques to calculate control limits that are used to determine

whether the sampling results show the establishment's process is

in (or out of) control.

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Sampling Regulatory Requirements 

◄. 

9 CFR 310.25 for cattle, sheep, goat 

. 

9 CFR 310.25 for cattle, sheep, goat 

◄. 

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Establishments that slaughter livestock and poultry are

required under the regulations to collect microbiological

8/19/2022

samples for indicator organisms, as specified:

• 9 CFR 310.25 for cattle, sheep, goat;

• 9 CFR 310.18(c) for swine;

• 9 CFR 381.65(g) for poultry; and

• 9 CFR 381.94(a) for ratites.

https://www.ecfr.gov/current/title-9/chapter-III

310.25 Contamination with microorganisms; process control verification criteria and

testing; pathogen reduction standards.

(a) Criteria for verifying process control; E. coli testing. (1) Each official establishment

that slaughters livestock must test for Escherichia coli Biotype 1 (E.coli) Establishments

that slaughter more than one type of livestock or both livestock and poultry, shall test

the type of livestock or poultry slaughtered in the greatest number. The establishment

shall:

(i) Collect samples in accordance with the sampling techniques, methodology, and

frequency requirements in paragraph (a)(2) of this section;

(ii) Obtain analytic results in accordance with paragraph (a)(3) of this section; and

(iii) Maintain records of such analytic results in accordance with paragraph (a)(4) of this

section.

310.25 (5)

Criteria for evaluation of results,

An establishment excising samples from carcasses is operating within the criteria when the

most recent E. coli test result does not exceed the upper limit (M), and the number of

samples, if any, testing positive at levels above (m) is three or fewer out of the most recent

13 samples (n) taken, as follows:

Type of livestock Lower limit of

marginal range (m)

Upper limit of

marginal range

(M)

Number of sample

tested

Maximum number

permitted in

marginal range

(c)

Cattle Negative* 100 CFU/cm2 13 3

Negative is defined by the sensitivity of the method used in the baseline study with a limit of

sensitivity of at least 5 CFU/cm 2 carcass surface area.

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9 CFR 310.25 for cattle, sheep, goat 

. 

9 CFR 310.25 for cattle, sheep, goat 

. 

9 CFR 310.25 for cattle, sheep, goat 

. 

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Establishments sponging carcasses shall evaluate E. coli test results using

statistical process control techniques.

(6) Failure to meet criteria. Test results that do not meet the criteria described in

paragraph (a)(5) of this section are an indication that the establishment may not

be maintaining process controls sufficient to preventfecal contamination. FSIS

shall take further action as appropriate to ensure that all applicable provisions of

the law are being met.

(7) Failure to test and record. Inspection shall be suspended in accordance with

rules of practice that will be adopted for such proceedings upon a finding by FSIS

that one or more provisions of paragraphs (a) (1)-(4) of this section have not been

complied with and written notice of same has been provided to the establishment.

Raw meat product performance standards for Salmonella. An establishment's raw meat

products, when sampled and tested by FSIS for Salmonella, as set forth in this section, may not

test positive for Salmonella at a rate exceeding the applicable national pathogen reduction

performance standard, as provided in Table 1 to this paragraph:

Table 1 to paragraph (b)(1) - Salmonella Performance Standards

Class of Product Performance Number of Samples Maximum number of

Standard (percent (%) tested (n) positivesto achieve

positive for Standard ( c )

Salmonella

Steers/heifers 1% 82 1

Cows/Bulls 2.7% 58 2

Ground Beef 7.5% 53 5

• FSIS will sample and test raw meat products in an individual

establishment on an unannounced basis to determine prevalence of

Salmonella in such products to determine compliance with the

standard. 

• The frequency and timing of such testing will be based on the

establishment's previous test results and other information

concerning the establishment's performance.

• In an establishment producing more than one class of product subject

to the pathogen reduction standard, FSIS may sample any or all such

classes of products. Further information on Pathogen Reduction:

https://www.sciencedirect.com/science/article/pii/S0749072015302863

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9 CFR 310.25 for cattle, sheep, goat 

◄. 

Sampling Regulatory Requirements 

. 

9 CFR 310.18 (Swine Slaughter) 

◄. 

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Noncompliance and establishment response. When FSIS determines that an establishment

has not met the performance standard:

(i) The establishment shall take immediate action to meet the standard.

(ii) If the establishment fails to meet the standard on the next series of compliance tests for

that product, the establishment shall reassess its HACCP plan forthat product and take

appropriate corrective actions.

(iii) Failure by the establishment to act in accordance with paragraph (b)(3)(ii) of this section, 

or failure to meet the standard on the third consecutive series of FSIS-conducted tests for

that product, constitutes failure to maintain sanitary conditions and failure to maintain an

adequate HACCP plan, in accordance with part 417 of this chapter, for that product, and will

cause FSIS to suspend inspection services. Such suspension will remain in effect until the

establishment submits to the FSIS Administrator or his/her designee satisfactory written

assurances detailing the action taken to correct the HACCP system and, as appropriate, other

measures taken by the establishment to reduce the prevalence of pathogens.

Let’s briefly look at the sampling requirements

for :

9 CFR 310.18(c) for swine; 

9 CFR 381.65(g) for poultry; and

9 CFR 381.94(a) for ratites. 

Official swine slaughter establishments, except for very low-volume

establishments, must collect and analyze carcass samples for microbial organisms

at the pre-evisceration and post-chill points in the process. Establishments that

slaughter more than one type of livestock must test the type of livestock

slaughtered in the greatest number. Establishments that bone their products

before chilling (i.e., hot-boned products) must collect and analyze samples at the

pre-evisceration point in the process and after the final wash instead of at postchill. Very low-volume establishments must collect and analyze samples for

microbial organisms at the post-chill point in the process. All swine establishments

must sponge or excise tissue from the ham, belly, and jowl areas.

(i) Very low-volume establishments annually slaughter no more than 20,000 swine, 

or a combination of swine and other livestock not exceeding 6,000 cattle and 20,000

total of all livestock.

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9 CFR 381.65 (g) (Poultry) 

◄. 

9 CFR 381.65 (g) (Poultry) 

. 

9 CFR 381.94 (a) -Ratites 

◄. 

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Official poultry slaughter establishments must develop, implement, 

and maintain written procedures to prevent contamination of

carcasses and parts by enteric pathogens and fecal contamination

throughout the entire slaughter and dressing operation. 

Establishments must incorporate these procedures into their HACCP

plans, or sanitation SOPs, or other prerequisite programs. At a

minimum, these procedures must include sampling and analysis for

microbial organisms in accordance with the sampling location and

frequency requirements in paragraphs (g)(1) and (2) of this section to

monitor their ability to maintain process control.

Sampling locations. Establishments, except for very small establishments

operating under Traditional Inspection or very low volume establishments

operating under Traditional Inspection must collect and analyze samples for

microbial organisms at the pre-chill and post-chill points in the process. Very

small establishments operating under Traditional Inspection and very low

volume establishments operating under Traditional Inspection must collect and

analyze samples for microbial organisms at the post-chill point in the process.

(i) Very small establishments are establishments with fewer than 10 employees

or annual sales of less than $2.5 million.

(ii) Very low volume establishments annually slaughter no more than 440,000

chickens, 60,000 turkeys, 60,000 ducks, 60,000 geese, 60,000 guineas, or 60,000

squabs.

Each official establishment that slaughters ratites shall test for Escherichia

coli Biotype I (E. coli). Establishments that slaughter ratites and livestock, 

shall test the type of ratites or livestock slaughtered in the greatest

number. The establishment shall: 

(i) Collect samples in accordance with the sampling techniques, 

methodology, and frequency requirements in paragraph (a)(2) of this

section;

(ii) (ii) Obtain analytic results in accordance with paragraph (a)(3) of this

section; and

(iii) (iii) Maintain records of such analytic results in accordance with

paragraph (a)(4) of this section.

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Statistical Process Control (generic E. coli) 

Statistical Process Control 

Sample Analysis 

◄. 

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• Statistical Process Control (SPC) for generic E. coli is required with

products that were not represented by the PR/HACCP Rule by a

performance standard, because no relevant baseline studies were

available at the time. 

• The generic E.coli results published in the Federal Register Notice

(2005) can complement SPC by providing establishments with an

additional measure of process control. 

https://www.govinfo.gov/content/pkg/FR-2005-02-17/pdf/05-3030.pdf

Chapter 5- Sample Analysis

• FSIS has developed performance criteria for beef using the excision sampling

technique. 

• Generic E. coli performance criteria are not enforceable regulatory standards. 

• Performance criteria are numbers published in the regulations that represent the

highest expected microbial loads on carcasses when the slaughter process is under

control. 

• They give livestock slaughter establishments guidance about the effectivenessof

their slaughter process in preventing fecal contamination. 

• Test results that meet the criteria in the regulations provide evidence that the

establishment is maintaining adequate process control for fecal contamination and

sanitary dressing.

• Some establishments conduct their own analyses. FSIS assumes establishments

following the "Guidelines for E. coli Testing for Process Control Verification in Cattle

and Swine Slaughter Establishments" will conduct their sampling in a manner that

does not jeopardize the integrity of the sample or the reliability of the test results. 

• https://www.fsis.usda.gov/sites/default/files/import/Guideline_for_Ecoli_Testing_Ca

ttle_Swine_Estab.pdf

• Because these guidelines are not regulatory requirements, the establishment may

choose to use a comparable sampling technique.

• Establishment laboratory employees might have a copy of the Association of Official

Analytical Chemists (AOAC) procedures or articles from peer-reviewed scientific

journals that describe their procedure. 

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Statistical Process Control 

◄. 

Verifying Statistical Process Control 

. 

Verifying Statistical Process Control 

◄. 

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An example of a method a company may use to develop a SPC program is as

follows. 

The establishment:

• Conducts a series of preliminary generic E. coli tests during operations

• Charts the results in CfU/cm2

• Collects test results long enough to have a true picture of its performance

(about 30 days usually)

• Determines the typical range of generic E. coli counts found normally

EIAO are to verify that the establishment is evaluating

the test results using statistical process control

techniques.

In this context, EIAO are to verify that an establishment

that uses statistical process control has assessed the

historical

―normal performance of the slaughter process when it

was in control and developed criteria that will indicate

8/19/2022

• Sets upper and lower control limits based on test results

when the process may not be in control.

EIAO are to verify that the establishment uses generic E. coli

testing results to identify times when the slaughter process is

trending toward a loss of control and takes necessary actions to

reestablish control. 

EIAO are not to focus on the particular method the

establishment uses to set process control criteria. 

Instead, they are to review the generic E. coli testing results and

verify that the establishment has set generic E. coli criteria to

define process control and responds to results outside those

criteria

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Statistical Process Control Chart example 

Statistical Process Control (E. coli Control Chart) 

-

Using Regulatory Performance Criteria (m/M 

Values) to Evaluate Test 

Results 

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• The following slide example of a SPC chart plots test results in terms of test number, 

along the horizontal X-axis, against cfu/cm2 on the Y-axis. This livestock slaughter

establishment set a centerline value for its process control, which indicates the

center point of the acceptable range of test results. 

• The upper control limit (UCL) line marks the highest test result value considered

acceptable by the company. The test result shown at test number 6 is above the

upper control limit. 

• The company recognized that this result was probably due to a variation in its

process that needed to be identified, eliminated, and prevented from recurring. 

• According to the chart, the establishment measures were effective because the

following test result was back in the acceptable range. 

E. Coli

Cfu/cm2

140

120

100

80

60

40

20

0

-20

x UCL

X x x x

x x x

1 3 5 7 11 13 15 17

Test Number

• Cattle establishments that choose excision of three sites must use the

m/M performance criteria published in the regulations for evaluating

test results when they are available. 

• Regulatory m/M criteria apply only to cattle sampling when the excision

sampling technique is used. 

• When performance criteria are published in the regulations, the E. coli

test results are compared to the regulatory criteria and

• may fall into one of three categories: acceptable, marginal (represented

by “m”), and unacceptable (represented by “M”). 

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18
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Using Regulatory Performance Criteria (m/M Values) to 

Evaluate Test 

Results 

Using Regulatory Performance Criteria 

(m/M Values) to Evaluate Test 

Results 

Using Regulatory Performance Criteria 

(m/M Values) to Evaluate Test 

Results 

I I I I 

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Marginal results (“m”) are those that fall within the worst 20% of overall

industry performance in terms of E. coli counts (results taken from

baseline study). 

More than three marginal results in the last 13 tests are

unacceptable.

• Results in the worst 2% of overall industry performance (results taken

from the baseline study) are called the maximum or “M” value. Any

single

test result exceeding “M” is unacceptable. 

• The m/M values taken from the regulations are applied to a moving window of

the last 13-documented test results.

• That means that the establishment considers all of the last 13 test results when

determining if the process is in control. 

• Every time a new test result is added to their records, the oldest test is dropped, 

and the new test becomes one of the most recent 13 results.

• For the slaughter process to be judged in control no more than three sample

results can be above the “m” marginal line. If four sample results are above

“m”, the process is out of control.

The following table from the regulations shows the m/M values for E. coli

performance criteria set by the Agency for excision testing of cattle. 

Species Lower Limit of

marginal range

(m)

Upper Limit of

marginal range

(M)

Number of

sample tested

(n)

Maximum #

permitted in

marginal range

( c )

Cattle Negative 100 CFU/cm2 13 3

An example of how to use the table is to consider a cattle slaughter

establishment that uses the excision sampling method. An E. coli test result is:

• Acceptable if it comes back negative

• Marginal if the test result is positive but not above 100 Cfu/cm2

• Unacceptable if it is above 100 Cfu/cm2

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Chapter 6-FSA Questions/Scenarios

The following scenarios are developed to help the EIAO answer questions in the FSA tools using statistics

to show process control.

You will be asked to answer some questions using the data provided to you.

For example:

General FSA Tool:

G5 Decision Making Analysis (1 to 2 pages) Provide an overall analysis of the FSA findings and the thought

process used to arrive at the FSA recommendation. The support for the recommendation is derived

from the sampling results (including the results from RLm, IVT, or IIT sampling), PHRE, in-plant

observations, and the HACCP system design and implementation documented in the tools. 

Scenario 1

The EIAO has been assigned to perform an FSA at a Red Meat (Cattle) Slaughter establishment.

Using 9 CFR 310.25 (5)...

The establishment is excising samples from carcasses to determine if it is operating within the criteria when

the most recent E. coli test result does not exceed the upper limit (M), and the number of samples, if any,

testing positive at levels above (m) is three or fewer out of the most recent 13 samples (n) taken, as follows:

CFU/ 55 66 Neg 78 112 77 105 109 33 77 109 Neg 55 cm2

Sample

# 1 2 3 4 5 6 7 8 9 10 11 12 13

QUESTION

FSA Meat Tool: M8 -Considering all source materials used (i.e., self-supply through slaughter and

outside source materials) and products produced (i.e., non-intact beef and non-intact beef

components), does the establishment have measures in place to support that STEC has been

reduced to below detectable levels and is a hazard “not reasonably likely to occur?”

Scenario 1-Discussion

Using 9 CFR 310.25 (5):Failure to meet criteria. Test results that do not meet the criteria described in paragraph (a)(5) of

this section are an indication that the establishment may not be maintaining process controls sufficient to prevent fecal

contamination. FSIS shall take further action as appropriate to ensure that all applicable provisions of the law are being

met.

Noting that samples 5, 7, 8, and 11 (4) are above the Upper Limit of 100 CFUs/cm2, what would be your response to the

question...

Does the establishment have measures in place to support that STEC has been reduced to below detectable levels and is a

hazard “not reasonably likely to occur?

Use the chart from the regulations to make your determination.

Species Lower Limit of

marginal range (m)

Upper Limit of

marginal range (M)

Number of sample

tested (n)

Maximum #

permitted in

marginal range ( c )

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

■■■■■■■■■■■■■■■ 

Cattle Negative 100 CFU/cm2

--

13 3

60

20
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Scenario 2

The EIAO has been assigned to perform an FSA at a Poultry Slaughter establishment.

Using 9 CFR 381.65 (g))...

Sampling locations.

Establishments, except for very small establishments operating under Traditional Inspection or very low

volume establishments operating under Traditional Inspection must collect and analyze samples for

microbial organisms at the pre-chill and post-chill points in the process. Very small establishments operating

under Traditional Inspection and very low volume establishments operating under Traditional Inspection

must collect and analyze samples for microbial organisms at the post-chill point in the process.

Poultry FSA Tool

Sampling and Testing for Process Control Organisms

P62 Does the establishment conduct sampling and testing for process control organisms? (NOTE: poultry

slaughter establishments are required to sample process control organisms, see Modernization of Poultry

Slaughter Inspection Final Rule for requirements 9 CFR 381.65 (g)?

Scenario 2

Information gathered by the EIAO when reviewing establishment records and discussion with management:

-EIAO review of the establishment pre-requisite program titled WOG Rinse, showed that the establishment

performs the sampling frequency equivalent to the regulatory frequency. One sample is taken per 22,000

birds as was observed during the FSA. WOG Rinse Records reviewed also showed this.

-EIAO review of the establishment’s sampling plan for generic E.coli showed that establishment uses the

regulatory sampling procedure and testing method. Direct observation of this sampling procedure showed

that the establishment is utilizing the regulatory sampling plan.

-EIAO review of the establishment generic E.coli testing results showed that over the past 60 days the

establishment has routinely met their limits as determined by m/M.

-EIAO conversation with establishment management showed that any unacceptable events or trends

associated with the generic E.coli testing results will prompt a further evaluation to determine whether or

not action is required. No positives above the regulatory levels in the last six months.

Scenario 2- Discussion

• Does the establishment conduct sampling and testing for process control

organisms? (NOTE: poultry slaughter establishments are required to sample

process control organisms, see Modernization of Poultry SlaughterInspection

Final Rule for requirements 9 CFR 381.65 (g)?

• Using the data provided, what would be the support for your answerto the

question?

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Statistical Process Control DeterminationWorkshop

In this workshop, you will be tasked to determine if an establishments sampling program is “in control.”

You will be given data that the establishment has collected from their Generic E.coli sampling program.

You will need to create a Statistical Process Control Chart. Use the data to determine the mean (m) and the

Standard Deviation (SD) from the mean to determine the Upper and Lower control limits (UCL/LCL).

Mean: The sum of the values divided by the number (N) of values.

Standard Deviation:

See next slide for data Cattle

Negative*

100 CFU/cm2

13

3

Sample # 1 2 3 4 5 6 7 8 9 10 11 12 13

CFU/c

m2

50 66 109 76 111 65 78 65 132 88 65 121 66

 

 

 

 

 

 

 

 

 

 

-

Workshop Answer Key

Step 1-Calculate the Mean (m):

50+66+109+76+111+65+78+65+132+88+65+121+66 / 13 = 1092 / 13 = 84 (Mean)

84 is the value we will use to calculate the Standard Deviation from the value

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Step 2: Finding ( x-μ2) Mean=84

Complete table below.

Data Point Dis6tance From Mean Square of Distance from Mean

50 50-84 = (-34) (-34)2 = 1156

66 66-84 = (-18) (-18)2 = 324

109 109-84 = (25) (25)2 = 625

76 76-84 = (-9) (-9)2 = 81

111 111-84 = (27) (27)2 = 729

65 65-84 = (-19) (-19)2 = 361

78 76-84 = (-8) (-8)2 = 64

65 65-84 = (-19) (-19)2 = 361

132 132-84 = (48) (48)2 = 2304

88 88-84 = (-4) (-4)2 = 16

65 65-84 = (-19) (-19)2 = 361

121 121-84 = (37) (37)2 = 1369

66 66-84 = (-18) (-18)2 = 324

Step 3: Finding the sum of (x-μ)2

The symbol ∑ means "sum", so in this step we add up the five values we found in

Step 2.

1156

324

625

81

729

361

64

361

2304

16

361

1369

324

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

-

-

8075 is the sum of the 13 values

Step 4: In this step, we divide our result from Step 3 by the variable N, which

is the number of data points. (We have 13 data points)

8075 / 13 = 621.15

Step 5: Just take the square root of the answer from Step 4 and we're done.

√621.15 = 24.92

The Standard Deviation from the mean of our data is 24.92

84 – 24.92 = 59.08 Lower Limit

24.92 + 84 =108.92 Upper Limit

Now we can place our values on the chart using the Mean and Upper and

Lower Control Limits

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-

···········-

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Mean

84

59.08

Lower

Limit

108.92

Upper

Limit

1 2 3 4 5 6 7 8 9 10 11 12 13

140

120

100

80

60

40

20

0

-20

-40

x x

x

x

x

x

x

x

x

x

x

x

x

Sample #

70

Process Control Determination

Since 4 data points are above the Upper Limit of 108.9

established by the Standard Deviation from the mean...

109

111

132

121

Forthe slaughter process to be judged in control no more than three sample results can be

above the “m” marginal line. If four sample results are above “m”, the process is out of

control.

It could be determined that this process is out of control

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