that the “superiority of the diary data may not be as obvious as the literature suggests.” In Tanzania, the mean number of transactions in the official Household Budget Survey diary declined by 10 percent from the 1<sup>st</sup> to 3<sup>rd</sup> survey month, and by 27 percent from the 1<sup>st</sup> to 13<sup>th</sup> (last) survey month (NBS, 2002), suggestive of inconsistent supervision of interviewers and/or diary fatigue on the part of respondents. In Malawi, nearly 40 percent of 10,698 households in the 1997/98 national household survey were judged to have incomplete or unreliable expenditure data due to poor maintenance of the diary (National Economic Council, 2000); this drastic waste of survey resources prompted the switch to recall consumption methods in the subsequent national household surveys in 2004 and 2010. In the case of the Russian Household Budget Survey, the pattern of non-response to the household diary, especially among wealthier households, generates extreme sample weights which Gibson and Poduzov (2003) conclude are inefficient from both a statistical and a budget perspective.

# _Level of Detail in Consumption Questionnaires_

The number of items about which data are collected is one of the central issues in designing a consumption module. National consumer price index baskets may have in excess of 300 items. To reduce the burden on respondents and survey activities in general, shorter lists of items are created by focusing on those items that represent the greatest share of consumption and aggregating other, less important, items into categories. At present, the number of consumption items (or categories) for which data are collected from households in LSMS surveys ranges from 37 to 305, with the mean being 137 and the median 130: the mean number of food items alone is 75.<sup>7</sup> This level of detail on consumption is thought to be important as it prompts respondents to remember more completely and accurately their consumption. But, the costs may be high: longer interview time, greater respondent fatigue and higher non-response.

While there are surprisingly few studies from developing countries evaluating the accuracy of shorter versus longer lists — none were identified from any African countries — it appears that more disaggregation and longer lists of items result in higher levels of recorded consumption. In El Salvador, data from 1994 showed that the longer, more detailed questions on consumption resulted in an estimate of mean household consumption that was 31 percent higher than that from the condensed version of the questionnaire (Jolliffe, 2001). This resulted in much higher poverty estimates from the short

> 7 Figures are calculated from the Comparative Living Standards Project data base. Note that although 100+ consumption items seems a large number, many Household Budget Surveys (HBS) will cover even more food items in the diary. HBSs usually do not collect much additional information on household socioeconomic conditions, whereas the LSMS surveys do, thereby necessitating both recall and food lists that are not exhaustive of all foods. The objective of an LSMS survey is consistent measurement of total consumption for each household in the sample, rather than accurate measures of commodity-specific consumption for the population.