## Reviewof Survey Datato Support Revisions to DOE'S Dishwasher Test Procedure Addendum

U.S. Department of Energy Energy Efficiency and Renewable Energy Office of Building Technology, State and Community Programs 1000 Independence Avenue, SW Washington, DC 20585

Date: March 5, 2002

Arthur D. Little, Inc. Acorn Park Cambridge, MA 02140 

## Review of Survey Data to Support Revisions to DOE's Dishwasher Test Procedure
Addendum

U.S. Department of Energy Energy Efficiency and Renewable Energy Office of Building Technology, State and Community Programs 1000 Independence Avenue, SVV Washington, DC 20585

Date: March 5, 2002

Arthur D. Little, Inc. Acorn Park Cambridge, MA 02140Addendum 

### The prime objective of this addendum is to expand on and readdress two areas of the report, 

### "Review ofSuweyData to Support Revisions toDOE'SDishwasher Test Procedure", prepared for the DepartmentofEnergy's Office ofBuilding Technology, State and Community Programs and issued December 18,2001. These areas are: 1. Toprovide more detail on the analysis in the section, Quantitative Amount of 

### Soilin a Dishwasher Load, a) Demonstrating the robustnessofthe prime source of data forthe analysis - 

### survey

### C, b) 

### Introducingand analyzing additional data from survey C, and c) Refocusingon survey C as the primary basis for determining the portion ofthe AHAM DW-1 soil load that could be used to represent light, medium, and heavy soil levels; and 

### 2. To clarify the rationale for the recommended 200 to 233 average-use cycles per year for a dishwasher.
Background on the Quantitative Amount of Soil in a Dishwasher Load 

### This section ofthe report drew from three surveys identifiedas SurveyC, Survey D, and SurveyF. Manufacturers and energy interest groupsprovided these surveys. As in the report, a key requirement of this addendum is to maintain the confidentiality ofthe industry survey sources. To this end no source is identified and only general informationon the data source is provided. Table 1 gives a comparative overview ofthe scope and size of these three surveys.
Table I

## - Overview of scope and size of surveys



### Surveys C, 

### D, and F, cumulatively representing over 2,000 U.S. households, provide text andfor graphic descriptions to link their categories ofthe level of soil to the three soil levels -

### Light, Medium, Heavy- and to quantitative amounts of soil for each level. ReferencingANSIIAHAM Standard DW-1 for the types of soil and, most importantly, the amountsof soil is essential in relating each of the three soil levels to an amount of soil. The relationship to the amountsof soil representative of the soil levels is derived differently for each survey, but for each survey the relationship is made in terms of

### the number of place settings

### in the DOE test load that are soiled according to ANSIIAHAM Standard DW-1. The results ofthe analysis to determine these relationships were presented in the report issued on December 18,2001, and reflect an aggregation ofthe data from surveysC, 

### D, and 

### F. Addendum The prime objective ofthis addendum is to expand on and readdress two areas ofthe report, "Review of Survey Data to SupportRevisions to DOE'sDishwasher TestProcedure", prepared for the Department ofEnergy's Office ofBuilding Technology, State and Community Programs and issued December 18, 2001. These areas are: 1. To provide more detail on the analysis in the section, QuantitativeAmountof Soil in a DishwasherLoad, a) Demonstrating the robustness ofthe prime source ofdata for the analysis

- survey C, b) Introducing and analyzing additional data from survey C, and c) Refocusing on survey C as the primary basis for determining the portion ofthe AHAM DW-I soil load that could be used to represent light, medium, and heavy soil levels; and 2. To clarify the rationale for the recommended 200 to 233 average-use cycles per year for a dishwasher.
Background on the Quantitative Amount ofSoil in a Dishwasher Load This section ofthe report drew from three surveys identified as Survey C, Survey D, and Survey F. Manufacturers and energy interest groups provided tJRese surveys. As in the report, a key requirement ofthis addendum is to maintain the confidentiality ofthe industry survey sources. To this end no source is identified and only general information on the data source is provided. Table I gives a comparative overview ofthe scope and size ofthese three surveys. Table 1 - Overview of scope and size of surveys

Nationally Representative Regional Limited Moderate Regional <i250 Moderate Moderate Surveys C, D, and F, cumulatively representing over 2,000 U.S. households, provide text and/or graphic descriptions to link their categories ofthe level ofsoil to the three soil levels

- Light, Medium, Heavy- and to quantitative amounts ofsoil for each level. Referencing ANSI! AHAM Standard DW-I for the types ofsoil and, most importantly, the amounts ofsoil is essential in relating each ofthe three soil levels to an amount ofsoil. The relationship to the amounts ofsoil representative ofthe soil levels is derived differently for each survey, but for each survey the relationship is made in terms ofthe number ofplace settings in the DOE test load that are soiled according to ANSI! AHA.M Standard DW-1. The results ofthe analysis to determine these relationships were presented in the report issued on December 18, 2001, and reflect an aggregation ofthe data from surveys C, D, and F.

2Detail on the Analysis of Quantitative Amount of Soil in a Dishwasher Load 

### The following sections describe in detail how the relationships between representative amounts of soil in a dishwasher load and the number ofplace settingsin the DOE test load that are soiled accordingto ANSIIAHAM DW-1 were developedfor surveys C, D, and F. Survey C 

### The authors of survey C determined representativeamounts of soil in a dishwasher load using an extensive set ofphotographs taken by consumers in their households ofthe soiled dishwarein their dishwasher. The data set of survey C 

### includes photos of both the lower and upper rack ofdishware for 5,849 cycles distributed across nearly 1,000U.S. households nationwide. Because ofthis photographicdata and other substantial data sets Survey C is considered the most robust and credible sourceof information to determine the amount of soil on the dishware in the dishwashersofU.S. households. In

### preparation ofthe report of December 18,2001,the authorsof surveyC 

### provided the results of their soil level analysis and a brief overview oftheir survey approach, photographic data, and soil level analysis. To prepare the following discussionon their analysisofquantitative amountsof soil in a dishwasherload, the authors of survey C provided additional detail information. Given this additionalinformation, a later section ofthis addendum refocuses the analysis and resultspresented in the report of December 18,2001to consider only survey 

### C. The authors of survey 

### C assessed their photographicdataby first establishinga Likert scale1 to compare and rank each photo. Their Likert scale has five levels for the lowerrack and five levels for the upper rack. Images of their Likert scale are shown 

### in the appendix. This assessment resulted in the distribution shown in Figure 1. The x-axis

### in Figure 1 runs from a value of 2 

### to a value of 10and represents the combined value of the Likert scalerankingsforthe lower and upper racks for each dishwasher load. For example, ifthe lower rack of a dishwasher load ranked a 3 and the upper rack a 1,it has a combined value of

### 4. The authors clusteredthe combined values into three levels -

### Light, Medium, and Heavy. The combined values of

### 2, 3, and 

### 4 were categorized as light. The combined values of 

### 5, 

### 6, and 7 

### were categorized as medium. The combined values of 8,9,and 10were categorized asheavy.

Likert scale -A response scale, developed by Rensis Likert,used for assessing opinions and usually consisting of 5 or more categories. As a semi-variable approach itprovides more information than the simple attribute (yes-no) question. 

### 3 Detail on the Analysis of Quantitative Amount of Soil in a Dishwasher Load The following sections describe in detail how the relationships between representative amounts of soil in a dishwasher load and the number ofplace settings in the DOE test load that are soiled according to ANSIIAHAM DW-l were developed for surveys C, D, and F. Survey C The authors ofsurvey C determined representative amounts ofsoil in a dishwasher load using an extensive set ofphotographs taken by consumers in their households ofthe soiled dishware in their dishwasher. The data set ofsurvey C includes photos ofboth the lower and upper rack ofdishware for 5,849 cycles distributed across nearly 1,000 U.S. households nationwide. Because ofthis photographic data and other substantial data sets Survey C is considered the most robust and credible source ofinformation to determine the amount ofsoil on the dishware in the dishwashers ofU.S. households. Inpreparation ofthe report ofDecember 18, 2001, the authors ofsurvey C provided the results of their soil level analysis and a briefoverview oftheir survey approach, photographic data, and soil level analysis. To prepare the following discussion on their analysis ofquantitative amounts ofsoil in a dishwasher load, the authors ofsurvey C provided additional detail information. Given this additional information, a later section ofthis addendum refocuses the analysis and results presented in the report ofDecember 18, 2001 to consider only survey C. The authors ofsurvey C assessed their photographic data by first establishing a Likert scale 1 to compare and rank each photo. Their Likert scale has five levels for the lower rack and five levels for the upper rack. Images oftheir Likert scale are shown in the appendix. This assessment resulted in the distribution shown in Figure 1. The x-axis in Figure 1 runs from a value of2 to a value of 10 and represents the combined value ofthe Likert scale rankings for the lower and upper racks for each dishwasher load. For example, ifthe lower rack ofa dishwasher load ranked a 3 and the upper rack aI, it has a combined value of4. The authors clustered the combined values into three levels

- Light, Medium, and Heavy. The combined values of2, 3, and 4 were categorized as light. The combined values of5, 6, and 7 were categorized as medium. The combined values of8,9, and 10 were categorized as heavy.

1 Likert scale - A response scale, developed by Rensis Likert, used for assessing opinions and usually consisting of5 or more categories. As a semi-variable approach itprovides more information than the simple attribute (yes-no) question. 3Figure 1

### - Distribution of Survey C results along its combined Likert scale

2 3 4 5 6 7 8 9 10 Combined Lower& Upper Rack Likert Scale Values


### A single combined value was selected from each soil level to facilitate more detailed evaluation and quantificationofthe photographic data to determine the amounts of soil representative ofeach soil level. For the light level the selected combined value was 

### 3. For the medium level the selected combined value was 6. 

### Forthe heavy level the selected combined value was 

### 10. Onreview of Figure 2, it is clear that the combined values selectedto representthe three soil levels -

### Light, Medium, and Heavy -

### were conservative choices. The selection ofthe combined value of 10to represent the heavy level was particularly conservative. Out of the 5,849 dishwasher cycles evaluated, only 18 cycles were foundto rank a combined value of 10. Approximately 12 sets of photos for each of the selected combined values were analyzed by a professional home economist. The home economist estimated the types and amounts ofthe food soils shown in the photos. The home economistthen expressed these estimates in terms of amounts of food soils listed in ANSIIAHAM Standard

### DW-1. With the amount of soil expressed in terms of 

### DW-1 food soils, a corresponding number of place settings that could be soiledper 

### DW-1with that amount of food soil was easily determined. Theresults ofthis analysis are shown in Table 2.
Table 2 

## - Results of survey C

* Of the 19 dishwasher cycles that ranked a 10 on the combined Likertscale, only 2 approached the quantity of food soil of 5 DW-1 soiled place settings. Figure 1 - Distribution of Survey C results along its combined Likert scale

35.0%

30.0% u >- u 

### '" v 00 ";25.0% '0 :; .2- :\l20.0% U >- ()

.... 

### ., .s::**~** 15.0%**~** .s:: III C '010.0% 

### c: 

## ., u :;; c.. 5.0%

0.0% 2 Arrows indicate the combined likert scale values selected to

----- represent ofthe amounts ofsoil for each ofthe soil levels.

3 4 5 6 7 8 Combined Lower & Upper Rack Likert Scale Values 9 10

A single combined value was selected from each soil level to facilitate more detailed evaluation and quantification ofthe photographic data to determine the amounts ofsoil representative ofeach soil level. For the light level the selected combined value was 3. For the medium level the selected combined value was 6. Forthe heavy level the selected combined value was 10. On review of Figure 2, it is clear that the combined values selected to represent the three soil levels

- Light, Medium, and Heavy

- were conservative choices. The selection ofthe combined value of 10 to represent the heavy level was particularly conservative. Out ofthe 5,849 dishwasher cycles evaluated, only 18 cycles were found to rank a combined value of 10. Approximately 12 sets ofphotos for each ofthe selected combined values were analyzed by a professional home economist. The home economist estimated the types and amounts ofthe food soils shown in the photos. The home economist then expressed these estimates in terms ofamounts offood soils listed in ANSI!AHAM Standard DW -1. With the amount ofsoil expressed in terms of DW-I food soils, a corresponding number ofplace settings that could be soiled per DW-I with that amount offood soil was easily determined. The results ofthis analysis are shown in Table 2.
Table 2 - Results of survey C Light Medium Heavy 

### 3 6 

### 10 * ::; 1/2 

### -2 <5
* Of the 19 dishwasher cycles that ranked a 10 on the combined Likert scale, only 2 approached the quantity of food soil of 5 DW-1 soiled place settings. r 4Survey D 

### For survey D the respondents directly select an amount of soil in terms of DW-1 soiled place settings. At a central testing location the authors of surveyD setup 6 images of a DW-1 place setting. Table 

### 3 describes the 6 images of a place setting, increasingly soiled according to DW-1, shownto survey respondents.
Table 3 

## - Description of the 6 images of a DW-1 soiled place setting shown to respondents in survey D



### Also shown in Table 

### 3 is how Arthur D. Little grouped the six images to the three soil levels -

### Light, Medium, and Heavy, and associated the images to a corresponding number of DW-1 soiledplace settingsin the DOE test load. Arthur D. Little's grouping of the six images was conducted in light of all of the available survey information and representsArthur D. Little's best judgement. Grouping image 

### 1 (Clean)with the light soil level, image

### 4 (50% DW-1) with the medium soil level, and image 

### 6 (100% DW-1) with the heavy soil level was straightforward. Judgement entered in groupingthe 3 

### remaining images. Image 2 (25% DW-1 rinsed) showed very little soil and clearly belonged in the light soil level. Image 3 

### (25% DW-1) appeared substantially less soiled than image 

### 4 and was grouped with the light soil level. Similarly,image 5 

### (75%DW-1) appeared only somewhat heavier soiledthan image 

### 4 and substantially less soiled than image 6, and was grouped with the medium soil level. Associating the images to a correspondingnumber ofDW- 1 soiled place settings in the DOE test load was very direct. Given that there are 8

### place settings in the DOE test load, the corresponding number ofDW-1 soiled place settings is the product of 8

### place settings times the percentage ofDW-1 soil. In the case of image 

### 2 (25% DW-1 rinsed), the corresponding number ofDW-1 soiled place settingsin the DOE test load was arrived atby splittingthe difference between that for image 1 (Clean) and image 3 

### (25% DW-1). Survey D For survey D the respondents directly select an amount ofsoil in terms ofDW-l soiled place settings. At a central testing location the authors ofsurvey D set up 6 images ofa DW-1 place setting. Table 3

.describes the 6 images ofa place setting, increasingly soiled according to DW -1, shown to survey respondents.
Table 3 - Description of the 6 images of a DW-1 soiled place setting shown to respondents in survey D

1 Clean 

## o 2 25% of DW-1 food soils rinsed with water Light 1 3 25% of DW-1 food soils 2 4 50% of DW-1 food soils 

### 4 5 75% of DW-1 food soils Medium 6 6 100% of DW-1 food soils Heavy 8
Also shown in Table 3 is how Arthur D. Little grouped the six images to the three soil levels

- Light, Medium, and Heavy, and associated the images to a corresponding number ofDW-l soiled place settings in the DOE test load. Arthur D. Little's grouping ofthe six images was conducted in light of all ofthe available survey information and represents Arthur D. Little's bestjudgement. Grouping image I (Clean) with the light soil level, image 4 (50% DW-l) with the medium soil level, and image 6 (100% DW-I) with the heavy soil level was straightforward. Judgement entered in grouping the 3 remaining images. Image 2 (25% DW-I rinsed) showed very little soil and clearly belonged in the light soil level. Image 3 (25% DW-I) appeared substantially less soiled than image 4 and was grouped with the light soil level. Similarly, image 5 (75% DW-l) appeared only somewhat heavier soiled than image 4 and substantially less soiled than image 6, and was grouped with the medium soil level. Associating the images to a corresponding number ofDW-l soiled place settings in the DOE test load was very direct. Given that there are 8 place settings in the DOE test load, the corresponding number ofDW-1 soiled place settings is the product of8 place settings times the percentage ofDW-I soil. In the case ofimage 2 (25% DW -1 rinsed), the corresponding number ofDW -1 soiled place settings in the DOE test load was arrived at by splitting the difference between that for image 1 (Clean) and image 3 (25% DW-l).

5

### Examples of the 

### images used in 

### survey D are 

### shown in 

### Figure 2. Figure 2 

## - Examples of the images of a DW-1 soiled place setting used in survey D Examples ofthe images used in survey D are shown in Figure 2. Figure 2 - Examples of the images of a DW-1 soiled place setting used in survey 0

6

### The authors interviewed respondents and asked them to selectthe image that most closely represents the level of soil on the dishware in their dishwasher. The results of survey D distributed as shown in Table4
Table 4 

## - Results of survey D



### As discussedin the report, the authors of survey 

### D noted that some number ofrespondentswere not properly interviewedand instructed prior to their selection of one ofthe soiledplace settingimages. The authors suspected that because of this lack of instruction respondents may have selected an imagebased on that image representing the amount offood soil in their dishwasher,rather than, as desired, selectingthe image that most closely representsthe level of soil on the dishware in their dishwasher. Survey F 

### For survey

### F, Arthur D. Little linked the survey's descriptionof its soil categoriesto an amountof soil in 

### terms of

### DW-1place settings. The authors of survey 

### F generated4 categories of soil level. Brief descriptions ofthose four categorieswere presented to the survey respondents. Table 5 

### describes the four categoriesof soil levelused in survey 

### F. and Arthur D. Little's assessment of the relation to the three soil levels -

### Light, Medium, and Heavy, and a corresponding number ofDW-I 

### soiledplace 

### settingsin the 

### DOE test load.
Table 5 

## - Description of the categories of soil level used in survey F



### Table 5 

### also showshow Arthur D. 

### Little grouped the four categoriesof survey 

### F to the three soil levels -

### Light, Medium, and Heavy, and associated the category descriptions to a corresponding number of DW-1 soiled place settings

### in the DOE test load. ArthurD. Little's grouping ofthe four Somewhat Clean Somewhat Dirty 

### VeryDirty Small particles of food left Onlythe largest chunks of food gone No or almost no

food removed Medium Heavy 4

8 The authors interviewed respondents and asked them to select the image that most closely represents the level ofsoil on the dishware in their dishwasher. The results ofsurvey D distributed as shown in Table 4
Table 4 - Results of survey D

As discussed in the report, the authors ofsurvey D noted that some number ofrespondents were not properly interviewed and instructed prior to their selection ofone ofthe soiled place setting images. The authors suspected that because ofthis lack ofinstruction respondents may have selected an image based on that image representing the amount offood soil in their dishwasher, rather than, as desired, selecting the image that most closely represents the level ofsoil on the dishware in their dishwasher. SurveyF For survey F, Arthur D. Little linked the survey's description ofits soil categories to an amount of soil in terms ofDW-1 place settings. The authors ofsurvey F generated 4 categories ofsoil level. Briefdescriptions ofthose four categories were presented to the survey respondents. Table 5 describes the four categories ofsoil level used in survey F. and Arthur D. Little's assessment ofthe relation to the three soil levels

- Light, Medium, and Heavy, and a corresponding number ofDW-l soiled place settings in the DOE test load.
Table 5 - Description of the categories of soil level used in survey F

Very Clean Somewhat Clean Somewhat Dirty Very Dirty All or almost all food gone Small particles of food left Only the largest chunks offood
No or almost no food removed Light

Medium

Heavy 1



### 4

8

Table 5 also shows how Arthur D. Little grouped the four categories ofsurvey F to the three soil levels

- Light, Medium, and Heavy, and associated the category descriptions to a corresponding number ofDW-I soiled place settings in the DOE test load. Arthur D. Little's grouping ofthe four

7

### categorieswas conductedin light of all of the available survey information and represents Arthur D. Little's bestjudgement. Grouping the Very Clean categorywith the light soil level and the Very 

### Dirty category with the heavy soil level was straightforward. Here, judgement entered in grouping the 

### 2 remaining categories. The Somewhat Clean category impliedvery little soil and clearly belonged in the light soil level. The Somewhat Dirty category implied much more food soilthan the Somewhat Clean category,but substantially less soiled than the Very Dirty category, and was grouped in the medium soil level. Associating the categoriesto a correspondingnumber ofDW-I soiled place settings in the DOE test load was less direct. Instead the soil levels were assigned a correspondingnumber of DW-I soiled place settings. Given that there are 

### 8place settingsin the DOE test load, the light soillevel was assigned 1DW-1 soiled place setting, the medium level -

### 4 DW-1 soiled place settings,and the heavy level - 

### 8 

### DW-1 soiledplace settings. The results of suivey F are shownin Table 

### 6.
Table 6 

## - Results of survey F categories was conducted in light ofall ofthe available survey information and represents Arthur D. Little's bestjudgement. Grouping the Very Clean category with the light soil level and the V**~ry** Dirty category with the heavy soil level was straightforward. Here, judgement entered in grouping the 2 remaining categories. The Somewhat Clean category implied very little soil and clearly belonged in the light soil leveL The Somewhat Dirty category implied much more food soil than the Somewhat Clean category, but substantially less soiled than the Very Dirty category, and was grouped in the medium soil leveL Associating the categories to a corresponding number ofDW-1 soiled place settings in the DOE test load was less direct. Instead the soil levels were assigned a corresponding number ofDW-1 soiled place settings. Given that there are 8 place settings in the DOE test load, the light soil level was assigned 1 DW-1 soiled place setting, the medium level - 4 DW -1 soiled place settings, and the heavy level- 8 DW-1 soiled place settings. The results ofsurvey F are shown in Table 6.
Table 6 - Results of survey F

8Summary of 

### Analysis 

### on Quantitative Amount of Soil in a Dishwasher Load 

### The following tables and figureresult directly from the review and analysis of surveys C, 

### D, and F outlined above. Thesetables and figure were discussed andpresented in the report ofDecember 18, 

### 200 

### 1. They are presented here again for clarityin demonstrating the progression ofthe detailed analysis to the results in the report ofDecember 18,200 

### 1. In 

### the following section the analysisand results will be reconsidered in light of the additional information provided by the authors of survey 

### C for this addendum. Table 7 is the consolidationofthe data found in Tables 2,4, 

### and 

### 6. Figure 

### 3 is the distributionofthat data weighted by the number of survey respondents. Table 8 shows the weighted averages ofthe distribution shown in Figure 3 

### for each ofthe three soil levels -

### Light, Medium, and Heavy.
Table 7 

### - Range of Survey Data on the Representative Amounts of Soil in the Three Soil Levels

Figure 3 

### - Distribution of Survey Respondents on Representative Amounts of Soil in Each of the Three Soil Levels



## 4 Heavy Soil Level

112 1 2 2 4 6 5 8 Number of Place Settings inthe DOE Test Load Soiled According to DW-1 Summary ofAnalysis on Quantitative Amount of Soil in a Dishwasher Load The following tables and figure result directly from the review and analysis ofsurveys C, D, and F outlined above. These tables and figure were discussed and presented in the report ofDecember 18, 2001. They are presented here again for clarity in demonstrating the progression ofthe detailed analysis to the results in the report ofDecember 18, 2001. In the following section the analysis and results will be reconsidered in light ofthe additional information providedby the authors ofsurvey C for this addendum. Table 7 is the consolidation ofthe data found in Tables 2, 4, and 6. Figure 3 is the distribution ofthat data weighted by the number ofsurvey respondents. Table 8 shows the weighted averages ofthe distribution shown in Figure 3 for each ofthe three soil levels

- Light, Medium, and Heavy.
Table 7 - Range of Survey Data on the Representative Amounts of Soil in the Three Soil Levels

Figure 3 - Distribution of Survey Respondents on Representative Amounts of Soil in Each of the Three Soil Levels 100%

90% Cii > CI> ..J 80% ·0 rJ) .s: 70% Light Soil Level u 

# .. - 1 Soiled Place w 

### .:: !l 60% !: CI> 

### " !: 50% 0cUI CI> 0:: 40% >- CI>**~** ::s rJ) 30% '0

.... !: CI> 20% u

... CI> 0.. 10%

0% 1/2 2 2 4 6 5 8 Number of Place Settings in the DOE Test Load Soiled According to DW-1

9Table 8

## - Representative Amounts of Soil in Each of the Three Soil Levels Found in Dishwashers of U.S. households Table 8 - Representative Amounts of Soil in Each ofthe Three Soil Levels Found in Dishwashers of U.S. households

10Additional Data from Survey C and Refocus of Analysis on Survey C 

### In the preparation ofthe report issued December 18,2001the authors of survey C 

### provided only the results of their analysis -

### the number of place settings

### in the DOE test load soiled per DW-1 as shown in Table 2, 

### and only a brief descriptionof their approach to the analysis. In preparation ofthis addendum the authors of survey 

### C provided a substantial amount of additional information to fill in the detail oftheir analysis. This additional information includes their Likert scale (Appendix), the ranking of their data against that Likert scale (Figure I), and a professional home economist's evaluation of the amount of soil shown in samples of the photographic data taken from the combined Likert scale rankings of 3,6,and 10. This section presents the evaluation of the professional home economist of survey C 

### and reconsiders the results of that evaluation. Recall from the discussionabove on survey 

### C that the authors of survey 

### C grouped their combined Likert scale rankings into three soil levels -

### Light, Medium, and Heavy. The combined Likert scale rankings of 2, 

### 3, and 4 

### were grouped into the light soil level. The combined Likert scale rankings of 

### 5, 6, and 7 

### were grouped into the medium soil level. The combined Likert scalerankings of 8, 9, and 10were grouped intothe heavy soil level. The combinedLikert scalerankings of 3,6, and 10were selected to representthe light, medium and heavy soil level,respectively. 

### A professional home economist analyzed a number of sets of photos for each ofthe combined Likert scalerankings of 3, 6, and 10. The home economist estimated the types and amounts offood soils shown in the photos. Table 9 lists the averages and medians ofthe mass offood soils estimated fi-om the samples ofphoto sets for the possible Likert scale combinations corresponding to the combined Likert scalerankings of 3, 6, and 10.
Table 9 -Averages and medians of the mass of food soils estimated by a home economist



### Translating these masses of food soilsto correspondingnumbers of place settings soiled according to ANSIIAHAM DW-1 is readily done given that DW-1 specifies approximately 3 1.3 grams of food soils per place setting as shown in Table 10. Light

Medium


### Heavy 3

6

10 211 313 412 

### 511 515 10 9 10 

### 10 18 12.7 27.0 52.3 72.3 109.5 10.85 24.9 50.25 62.5 115.8 Additional Data from Survey C and Refocus of Analysis on Survey C
In the preparation ofthe report issued December 18, 2001 the authors ofsurvey C provided only the results oftheir analysis

- the number ofplace settings in the DOE test load soiledper DW

### -1 as shown in Table 2, and only a briefdescription oftheir approach to the analysis. In preparation ofthis addendum the authors ofsurvey C provided a substantial amount ofadditional information to fill in the detail oftheir analysis. This additional information includes their Likert scale (Appendix), the ranking oftheir data against that Likert scale (Figure 1), and a professional home economist's evaluation ofthe amount ofsoil shown in samples ofthe photographic data taken from the combined Likert scale rankings of3, 6, and 10. This section presents the evaluation ofthe professional home economist ofsurvey C and reconsiders the results ofthat evaluation. Recall from the discussion above on survey C that the authors ofsurvey C grouped their combined Likert scale ranlcings into three soil levels

- Light, Medium, and Heavy. The combined Likert scale ranlcings of2, 3, and 4 were grouped into the light soil level. The combined Likert scale rankings of 5, 6, and 7 were grouped into the medium soil level. The combined Likert scale rankings of8,9, and 10 were grouped into the heavy soil level. The combined Likert scale rankings of3, 6, and 10 were selected to represent the light, medium and heavy soil level, respectively.
A professional home economist analyzed a number ofsets ofphotos for each ofthe combined Likert scale rankings of3, 6, and 10. The home economist estimated the types and amounts offood soils shown in the photos. Table 9 lists the averages and medians ofthe mass offood soils estimated from the samples ofphoto sets for the possible Likert scale combinations corresponding to the combined Likert scale rankings of3, 6, and 10.
Table 9 - Averages and medians of the mass of food soils estimated by a home economist

Light 3 

### 211 10 12.7 10.85 3/3 9 27.0 24.9 Medium 6 4/2 10 52.3 50.25 5/1 

### 10 

### 72.3 62.5 Heavy 10 5/5 18 109.5 115.8 Translating these masses offood soils to corresponding numbers ofplace settings soiled according to ANSIIAHAM DW-l is readily done given that DW-l specifies approximately 31.3 grams offood soils per place setting as shown in Table 10.

11Table 10

# - Averages and medians of the number of DW-1 soiled place settings based on the estimated masses of food soils in Table 9



### Comparing Table 10 to the results initially providedby the authors of survey 

### C in Table 

### 2 further indicates the conservatism of the authors in interpreting the results oftheir analysis. Discussions with the authors of survey 

### C indicated that the average number ofDW-1 soiled place settings in Table 10 were roundedup to yield the results that they had reported in Figure 

### 2. However, their reported value of <5 

### DW-I soiled place setting for the heavy soil level seems inconsistent with simple rounding upward of the averages for the number ofDW-1 soiled place settings. It appears more consistent with a value that represents an 

### extreme bound. This inconsistencyis addressed in the following recommendations. Light

Medium

Heavy 3

6

10 211 313 412 511 515 10 

### 9 10 10 18 0.41 0.86 1.67 2.31 3.50 0.35 0.80 1.61 2.00 3.70 Table 10

- Averages and medians of the number of DW-1 soiled place settings based on the estimated masses of food soils in Table 9

Light 3 2/1 

### 10 0.41 0.35 3/3 

### 9 0.86 0.80 Medium 6 

### 4/2 

### 10 1.67 1.61 5/1 

### 10 2.31 2.00 Heavy 

### 10 515 18 3.50 3.70 Comparing Table 10 to the results initially provided by the authors ofsurvey C in Table 2 further indicates the conservatism ofthe authors in interpreting the results oftheir analysis. Discussions with the authors ofsurvey C indicated that the average number ofDW -1 soiled place settings in Table 10 were rounded up to yield the results that they had reported in Figure 2. However, their reported value of<5 DW-I soiled place setting for the heavy soil level seems inconsistent with simple rounding upward ofthe averages for the number ofDW-1 soiled place settings. It appears more consistent with a value that represents an extreme bound. This inconsistency is addressed in the following recommendations.

12Clarification on the Recommended Range of Average-use Cycles per Year 

### The report ofDecember 18,2001presented three approaches to establisha number for the averageuse cyclesper year of a dishwasher. The first approach referenced the Energy Information Administration's 1997 ResidentialEnergy Consumption Survey (1997 RECS) as a large,welldocumented, and publicly available study on the average-use ofa dishwasher. Although a large and well-documented survey, 1997RECS use ofonly three response categories, two ofwhich were unbounded, made determining an averagenumber difficult. The 1997 RECS data on average-use of a dishwasher did clearly indicate that 50 percent ofitsrespondents use a dishwasher4 

### or less times per week, or approximately208 times per year. The 1997RECS set a target area for the number of average-use cyclesper year. The second approach consideredfive nationally representative surveys (surveys A, 

### B, G, 

### H, and 1997 RECS) using consistent definitionsfor the broad or unbounded categories ofthe surveys'. A low value, 

### an average value, and a high value were defined for each category found in the surveys. These values were used to calculate three averages for each survey -

### one average using the low values, a second average using the 'average' values, and a third average using the high values. As presented in the report ofDecember 18,2001 the averages oftheses averageswere 180for the low values, 206 for the average values, and 233 for the high values. This approach produced averages centered near the target area setby 1997RECS and established a range, although broad, for the number of average-use cycles per year. The third approach narrowed the range for the number of average-use cyclesper year by building on the previous approaches. The first approachusing the 1997RECS data set a target area for the number of average-use cycles per year. The second approach produced averagescentered on this target area and suggestedthat all ofthe available data pointed to this target area. The third approach used a weighted average to test whether the relative sizes ofthe five surveys would skew the averages from the target area. Using the average values for the categoriesofthe five surveysfi-omthe second approach, an average weightedby the number ofrespondents in each survey was calculated. This calculation yielded a weighted average of 200 average-use cyclesper year. As this weighted average of the five nationallyrepresentative surveys, was near the target area and near the middle of the previously calculated range of averages, it indicated that the size ofno one survey dominated over the others. This weighted average became the new minimum ofthe range for the number of average-use cyclesper year. Therefore,the lower end ofthe broad range established in the previous approach moved up from 180to 200 average-use cycles per year. The above analyses of available survey data on the frequency ofhouseholds' usage of a dishwasher set a range for the number of average-use cycles per year. The lower end ofthis range, 200, was set by the third approach and the upper end of this range, 233,remained at the high average setby the second approach. To refine this recommended range further additional data for the representative average-use cyclesper year was sought from the dishwasher detergent industry. This additional data was anticipated for late December 2001 or early January 2002, however no additional data has been made available to augmentthe recommendation. Clarification on the Recommended Range of Average-use Cycles per Year The report ofDecember 18, 2001 presented three approaches to establish a number for the averageuse cycles per year ofa dishwasher. The first approach referenced the Energy Information Administration's 1997 Residential Energy Consumption Survey (1997 RECS) as a large, welldocumented, and publicly available study on the average-use ofa dishwasher. Although a large and well-documented survey, 1997 RECS use ofonly three response categories, two ofwhich were unbounded, made determining an average number difficult. The 1997 RECS data on average-use ofa dishwasher did clearly indicate that 50 percent ofits respondents use a dishwasher 4 or less times per week, or approximately 208 times per year. The 1997 RECS set a target area for the number of average-use cycles per year. The second approach considered five nationally representative surveys (surveys A, B, G, H, and 1997 RECS) using consistent definitions for the broad or unbounded categories ofthe surveys'. A low value, an average value, and a high value were defined for each category found in the surveys. These values were used to calculate three averages for each survey - one average using the low values, a second average using the 'average' values, and a third average using the high values. As presented in the report ofDecember 18,2001 the averages oftheses averages were 180 for the low values, 206 for the average values, and 233 for the high values. This approach produced averages centered near the target area set by 1997 RECS and established a range, although broad, for the number ofaverage-use cycles per year. The third approach narrowed the range for the number ofaverage-use cycles per year bybuilding on the previous approaches. The first approach using the 1997 RECS data set a target area for the number ofaverage-use cycles per year. The second approach produced averages centered on this target area and suggested that all ofthe available data pointed to this target area. The third approach used a weighted average to test whether the relative sizes ofthe five surveys would skew the averages from the target area. Using the average values for the categories ofthe five surveys from the second approach, an average weighted by the number ofrespondents in each survey was calculated. This calculation yielded a weighted average of200 average-use cycles per year. As this weighted average ofthe five nationally representative surveys, was near the target area and near the middle ofthe previously calculated range ofaverages, it indicated that the size ofno one survey dominated over the others. This weighted average became the new minimum ofthe range for the number ofaverage-use cycles per year. Therefore, the lower end ofthe broad range established in the previous approach moved up from 180 to 200 average-use cycles per year. The above analyses ofavailable survey data on the frequency ofhouseholds' usage ofa dishwasher set a range for the number ofaverage-use cycles per year. The lower end ofthis range, 200, was set by the third approach and the upper end ofthis range, 233, remained at the high average set by the second approach. To refine this recommended range further additional data for the representative average-use cycles per year was sought from the dishwasher detergent industry. This additional data was anticipated for late December 2001 or early January 2002, however no additional data has been made available to augment the recommendation.

13Recommendations 

### Given the depth of the additional information provided by the authors of survey C 

### and the detail of the analysis of survey 

### C presented in this addendum, it is Arthur D. Little's recommendation that the data of survey 

### C stand as thebasis for determining the amount of soil on dishware inthe dishwashers of U.S. households. However, Arthur D. Little also recommends that the survey 

### C results reported in Table 2 

### should be modified to more closely reflect the approach ofrounding upward the average number ofDW-1 soiled place settings in Table 10. To this end the number ofDW-1 soiled place settings corresponding to the heavy soil level shouldbe set equal to 4. 

### Table 11 displays the number of DW-1 soiled place settings reportedby the authors of survey 

### C and highlights the modified number ofplace settings recommended by Arthur D. Little onreview of greater detail from survey C.
Table 11

## - Revised recommendation on the number of DW-1 soiled place settings corresponding to the soil levels



### To be consistent with the recommendationto let survey C 

### stand asthe basis for determining the amount of soil on dishware in the dishwashers of U.S. households, it is important to revisit the distribution of U.S. households by the level of soil in dishwasher loads (December 18,2001report, Figure 2). In the report of December 18,2001this distribution was based on 

### an aggregation of surveys A and C. 

### As discussed in 

### the report both surveys A and 

### C are large, nationally representative surveys and both present very similar data onthe qualitative level of soil 

### in dishwasher loads. Talung survey C 

### alone would shift this distribution somewhat from the medium soil level to the light soil level. However, ignoring survey A would be discounting a quality survey. Therefore, Arthur D. Little further recommends that the distribution of 

### U.S. households by the level of soil in dishwasher loads should stand as it was presented in the report of December 18,2001. Recommendations Oiven the depth ofthe additional infonnation provided by the authors ofsurvey C and the detail of the analysis ofsurvey C presented in this addendum, it is Arthur D. Little's recommendation that the data of survey C stand as the basis for detennining the amount ofsoil on dishware inthe dishwashers ofU.S. households. However, Arthur D. Little also recommends that the survey C results reported in Table 2 should be modified to more closely reflect the approach ofrounding upward the average number ofDW-1 soiled place settings in Table 10. To this end the number ofDW-l soiled place settings corresponding to the heavy soil level should be set equal to 4. Table II displays the number ofD W-I soiled place settings reported by the authors ofsurvey C and highlights the modified number ofplace settings recommended by Arthur D. Little on review ofgreater detail from survey C.
Table 11 - Revised recommendation on the number of DW-1 soiled place settings corresponding to the soil levels

To be consistent with the recommendation to let survey C stand as the basis for detennining the amount ofsoil on dishware in the dishwashers ofU.S. households, it is important to revisit the distribution ofU.S. households by the level ofsoil in dishwasher loads (December 18, 200I report, Figure 2). In the report ofDecember 18,2001 this distribution was based on an aggregation of surveys A and C. As discussed in the report both surveys A and C are large, nationally representative surveys and both present very similar data on the qualitative level ofsoil in dishwasher loads. Taking survey C alone would shift this distribution somewhat from the medium soil level to the light soil level. However, ignoring survey A would be discounting a quality survey. Therefore, Arthur D. Little further recommends that the distribution ofU.S. households by the level ofsoil in dishwasher loads should stand as it was presented in the report ofDecember 18, 2001.

14Appendix 

### - Survey C Likert scale Appendix

- Survey C Likert scale



### A1Appendix 

## - Survey C Likert scale Appendix

- Survey C Likert scale



# 2

2 

### A2Appendix 

## - Survey C Likert scale Appendix

- Survey C Likert scale

3 A3Appendix 

## - Survey C Likert scale Appendix

- Survey C Likert scale

4 A4dix 

### - Survey C Likert scale Appendix

- Survey C Likert scale

5 A5