THE EFFECTS OF FORMAT CHANGES ON REPORTING IN THE 1991 CONSUMER EXPENDITURE

DIARY SURVEY

Clyde Tucker, Bureau of Labor Statistics

2 Massachusetts Ave., NE, Rm. 4915, Washington, DC 20212

INTRODUCTION

Diaries have been used extensively to collect data in 

fields as diverse as transportation and health 

(Roghman and Haggerty 1972; Thompson, et al. 1977, 

Harkins 1979; Verbrugge 1980). Diaries also have 

been an important source of information on consumer 

spending for some time (Pearl and Levine 1971; Ruck, 

Waksberg, and Kaitz 1971) because they are 

particularly good instruments for collecting small, 

inexpensive items. The Bureau of Labor Statistic's 

(BLS) in conjunction with the Bureau of the Census, 

conducted a consumer expenditure survey that 

included a diary during 1972 and 1973 in the United 

States. A similar survey has been ongoing in the U.S. 

since 1980.

Much research has been devoted to the topic of 

consumer expenditure diary methodology. Several 

studies have compared the differences in the estimates 

from personal interviews involving recall and those 

from diaries (See Neter and Waksberg 1965; Stanton 

and Tucci 1982; Silberstein and Scott 1992). As 

Grootaert (1986) has pointed out, the results from the 

studies are inconclusive. One method may be superior 

over the other for some expenditures, but the reverse 

seems to be the case for other expenditures. 

Silberstein and Tucker ( Silberstein and Scott 11991; 

Silberstein 1991; Tucker 1992 ) have looked at 

various measures of error in the U.S. Consumer 

Expenditure Diary Survey (CE Diary).

Variations in diary procedures also have been 

examined. One group of studies has dealt with the 

effects of placing multiple diaries in a household as 

opposed to only one diary. Generally speaking, 

providing a diary to every family member over a 

certain age produces better reporting than having one 

member keep a diary for the entire family (Kemsley 

and Nicholson 1960; Sudman and Ferber 1971). On 

the other hand, in addition to the difficulty in 

obtaining cooperation from all participating family 

members in the multiple-diary situation, Grootaert 

(1986) found that proxy reporting was better where 

elderly respondents were concerned. As for the other 

aspects of diary methodology which have been 

investigated, they include length of the reporting 

period, the format of the diary itself, and die impact of 

incentives (Turner 1961; Sudman and Ferber 1971; 

Walsh 1977; Nashohn, Lindstrom, and Lindkvist 

1989). Respondents typically report more items at the 

beginning of the reporting period than at the end. This 

probably reflects a loss of interest in keeping the diary 

due to the tediousness of the task:.

There is evidence that diaries organized according to 

commodity categories produce the best results and 

that incentives can increase response rates. 

The experiment reported here continues in the 

tradition of those which have examined variations in 

diary methodology. It builds upon an earlier study 

conducted by the BLS and the Census Bureau to test 

several methods for collecting consumer expenditure 

information using a diary. Although survey 

procedures can have dramatic effects on response 

quality, these effects often are complicated and, thus, 

not easily measured. This problem is dealt with here 

by examining the effects from a variety of 

perspectives, including both the level and the 

distribution of expenditure reports for different 

commodities. The results are drawn together to arrive 

at overall conclusions about the relative merits of 

each methodology.

The next section provides, some general information 

about the BLS Consumer Expenditure Diary Survey. 

Section 3 describes the previous study as well as the 

design for the present one. Various measures of 

performance are defined in Section 4, and Section 5 

describes the statistical methodology used. Sections 6 

and 7 provide results and conclusions, respectively.

THE CONSUMER EXPENDITURE DIARY 

SURVEY

The Consumer Expenditure (CE) Diary Survey is 

conducted by the Bureau of the Census for the BLS 

and provides, along with the CE Quarterly Interview 

Survey, the information needed to construct the cost 

weights for the Consumer Price Index. The data also 

are used for economic analysis. Although the diary 

was designed to collect all daily expenditures made 

within the primary sampling unit (PSU), or locally, 

over a two-week period; as mentioned previously, it is 

especially effective for gathering information about 

small, frequently purchased items which are normally 

difficult to recall over an extended period. These 

expenditures include grocery items, meals eaten out, 

household supplies and personal care products and 

services. Data also are collected on the income, work 

experience and demographic characteristics using a 

household characteristics questionnaire.

The unit of analysis in the CE Diary, and the level at 

which most data are collected, is the consumer unit. A 

consumer unit is defined as one of the following: (1) 

the collection of all members of a household who are 

related by blood, marriage, adoption or other legal 

arrangement; (2) a person living alone or sharing a
household with others or living as a roomer in a private 

home or lodging house or in a permanent living 

quarters in a hotel or motel, but who is financially 

independent; or (3) two or more persons who live 

together and pool their incomes to make joint 

expenditure decisions. To be considered financially 

independent, at least two of the three major expense 

categories (housing, food and other living expenses) 

have to be provided by the respondent.

The CE Diary sample is designed to be representative

of the national, noninstitutional civilian population. 

Besides the population residing in regular housing, 

persons residing in selected group quarters, such as 

college dormitories, also are represented. Five to six 

thousand consumer units are interviewed each year 

from a nationwide two-stage, clustered design with 101 

PSUs (primary sampling units). Because the design is 

complex, a set of 44 balanced, half-sample replicate 

weights is constructed for use in variance estimation. 

The weights are assigned to each consumer unit in the 

survey in order to provide estimates for the U.S. 

population. For further a description see U.S. 

Department of Labor (1986).

DESIGN OF THE 1991 CE DIARY TEST

Previous research on item reporting rates indicated 

that explicit references to particular products in the 

diary can have a positive effect on the reporting of 

these items, especially if the reporting rates are low to 

begin with (Silberstein 1983 and Tucker 1984). In 

1985, a field test was undertaken to evaluate two 

experimental diary formats which provided more 

explicit information about what commodities should be 

reported. These diaries covered fewer expenditure 

categories than the diary that was being used. In 

particular, the apparel section and some other nonfood 

categories were eliminated. Respondents also were not 

required to specify the quantity and weight of items, as 

was the case in the current production diary.

Another feature of the experimental diaries was a new 

method for collecting recalled expenditures. 

Interviewers had been recording these expenditures 

directly into the diary using unscripted procedures and 

also asking a series of follow-up questions called 

"diary-check items" about some specific commodities 

often forgotten by respondents. The new procedure 

involved a scripted recall section for each expenditure 

category and was contained in the household 

characteristics questionnaire. Thus, recalled 

expenditures could be identified, and the rather 

cumbersome check items were eliminated.

What distinguished the two experimental diaries 

from one another was the specificity of the item 

descriptions in each commodity section. One diary, 

referred to as the "nonspecific," had blank lines for 

recording purchases under each of the section 

headings, and the headings contained relatively

extensive descriptions of items in that section. The 

second diary, the "specific," had only category titles 

in the headings, but the lines beneath each heading 

had specific items printed on them. Respondents just 

checked if an item was purchased and recorded the 

price. 

Extensive analyses (Tucker and Bennett 1988; Sliwa 

1988; Tucker 1992) showed that both of the 

experimental diaries produced gains in expenditure 

reports for groceries, but the specific diary gave the 

greatest overall improvement. The additional recall 

section proved to be worthwhile not only in 

uncovering forgotten expenditures but also in 

reducing interviewer errors common to the 

check-item section.

Before a new diary format could be implemented, 

several issues still needed to be addressed. Any new 

diary would have to incorporate the categories not 

covered on the experimental diaries. It was unclear 

how these additional categories would affect reporting 

by increasing respondent burden. Furthermore, 

although the specific diary seemed to be the better of 

the two, the number of printed lines would be very 

large if all nonfood categories were included. Also, 

follow-up work done in a laboratory suggested that 

respondents had difficulty correctly selecting the 

appropriate line for recording some expenditures in the 

specific diary (Tucker, Vitrano, Miller, and Doddy 

1989). 

For these reasons, it was decided that a second field 

test would evaluate a diary similar to the current 

production diary and an expanded version of the 

nonspecific diary which included all expenditure 

categories. Diary A, the one almost identical to the 

production diary, had two pages for recording 

expenditures each day. Diary B, the expanded 

nonspecific diary, had six pages per day containing a 

number of sections with headings describing which 

items should be recorded in them. The recall section 

was used with both, and, again, no quantity or weight 

information was collected. To save money, a separate 

test was not done. Instead, these two diaries replaced 

the diary currently being used with the production 

sample.

Both diaries were in the field for calendar years 1991 

and 1992, and each consumer unit was asked to keep 

the same diary for two consecutive weeks. Because 

Diary A was so similar to the production diary, 80% 

of the sample used it. Diary B was given to the other 

20%. Over 4500 consumer units received Diary A in 

1991, yielding 9170 weekly diaries treated as 

independent observations. There were 2264 weekly B 

diaries. The analysis is based on the 1991 data.

OUTCOME MEASURES

Several measurements are taken in order to evaluate 

the results of the test from a variety of perspectives. 
To facilitate comparisons between the diaries using 

these variables, commodities are grouped into 

expenditure categories. They are Food at Home, Food 

Away From Home, Apparel, Other Nonfood Items.

Perhaps the most important respondent performance 

measure is the reported mean weekly expenditure for 

each category. Mean weekly expenditure is computed 

in the following way for each expenditure category:

The measure of decline within a diary week, called 

first-day bias, compares the mean expenditure for the 

first day of the week to the average daily expenditure 

for that week. This is done for respondents who 

completed both diaries. Recalled expenditures are 

eliminated from the calculations and those 

respondents whose entire expenditure report was 

obtained from recall are not included. The first-day 

bias is computed as follows:

ANALYTICAL METHODS

The most important survey performance measures 

are mean expenditures and response (noninterview) 

rates, but relative importances are of at least equal 

interest since changes in them could affect the CPI. 

Therefore, treatment differences in all three indicators 

are subjected to significance testing at the .10 level. 

Given the computationally intensive nature of the
reasonably comparable to Diary A. Differences in 

relative importances that can be tied to improvements 

in reporting will be viewed positively.

RESULTS

To be sure that differences between the diaries are 

not simply a reflection of differences in sample 

characteristics, three variables were 

examined-consumer unit size and income and the 

percentage of incomplete income reporters. The first 

two are closely related to expenditures, and the last 

gives some indication of level of respondent 

cooperation. Table 1 provides the information about 

these indicators in both samples. Statistical tests 

using variances taking into account the complex 

design showed no differences between the samples. 

Table 2 gives the nonresponse rates for both diaries. 

Again, there are no statistically significant 

differences. 

The expenditure means for the four categories in 

Table 3 are higher in Diary Bin every case, although 

statistically significant differences are limited to Food 

At Home and Other Nonfood Items. Table 4 provides 

information on the other reporting measures. There is 

no consistent pattern among the reporting rates, with 

only the difference for Apparel approaching the 10% 

mark. A clearer trend in favor of Diary B might have 

been expected given the differences in expenditure 

means. There is more than a 10% difference in 

number of expenditure records for Food at Home. 

This difference coincides with the expenditure 

differences reported in Table 3. On the other hand, 

the number of records for Food Away From Home is 

greater for Diary A. The numbers in the other two 

categories are almost identical.

Taming to the other important measure, relative 

importances, Table 5 gives these for the four 

expenditure categories. No statistically significant 

differences exist; and, in fact, there are none of any 

substantive interest. The proportion for Food Away 

From Home is slightly smaller (about 8%) for Diary B 

because the increase in its mean expenditure was so 

much smaller than those for the other categories.

Table 6 contains the data on first-day and first-week 

biases, and they show the same pattern as in the Diary 

Operational Test. There is generally a greater firstday 

bias in Diary B; but the first-week bias is, if anything, 

in the opposite direction. This is particularly true for 

Apparel. These results may indicate that first-day bias 

is simply a matter of higher reports at the beginning of 

each diary week for Diary Bas opposed to a larger 

decline in effort later in the week.

CONCLUSIONS

The results of this study indicate that Diary B 

performs better than Diary A in prompting 

expenditure reports in most categories. Furthermore,
the response rates in the two diaries are comparable; 

and the relative importances for the different 

expenditure categories would remain about the same 

if Diary B were used. Thus, it is recommended that 

Diary B be used in the future; however, a more 

indepth analysis should be undertaken. In particular, 

the different response pattern for Food Away From 

Home should be examined more closely. Also, a 

better understanding of the different responses to the 

two diaries by various subpopulations is needed.

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