# _Consumption Aggregate_

We construct annual consumption aggregates (total household consumption expenditure) consistent with standard practices (see Deaton and Zaidi, 2002) but adapted to module specifications. For modules with the quantity of own-produced consumption but not shilling values (modules 1-3), monetary values were computed from unit values constructed from household information on purchases.<sup>18</sup> In each of the three modules, about 50 percent of quantities were able to be transformed by household-specific unit values (i.e., households also purchased the item), while in 25 percent of the cases the unit in which the household reported own-produced consumption was Tanzanian shillings. In the diaries, for each item we take the quantities reported minus what was recorded as sold or given away (deducted from the value as a percentage). Non-item specific (lump sum) corrections were made for changes in stocks (added consumption from stocks and adjusted for recorded acquisitions that were stocked instead of consumed), for food given to animals, and for items that were recorded as “forgotten.”<sup>19</sup> Module 3 stands out since it explicitly does not cover the same range of food as the other modules. Rather it is a subset list of the most frequently consumed foods based on the Household Budget Survey data. We scale food totals measured with this module up by 29.87 percent in order to compare with totals from the other modules, which are all covering a broader universe of foods (as stated earlier, we base this scaling up on the Household Budget Survey, where this subset of goods accounts for 77 percent [=1/(1+0.2987)] of total food consumption). For every module, we exclude expenditures on taxes and ceremonies. These consumption categories are not typically included in consumption aggregates due to their idiosyncratic nature and infrequency.

The direct comparison of results from the different survey modules sheds light on the relative influences of the various reporting errors discussed in Section 2. Since the frequently supervised personal diary is believed the most accurate in that it minimizes the magnitude of recall lapse, telescoping, and missed individual consumption, comparisons with this benchmark will be of particular use in understanding the net impact of the different reporting errors in each of the

> 18 For non-purchased products, we used the first available unit price in the following order: (i) Household-specific unit value, only available if household also purchased item (values more than five standard deviations from the district median price were replaced with district medians); (ii) EA median unit value; (iii) District median unit value; (iv) Overall median unit value; (v) EA median price from price questionnaire; (vi) District median from price questionnaire; (vii) Overall median from price questionnaire; and (viii) A price assigned by EDI staff, using best guesses based on the prices of similar items or units in the EA or district - only a handful of consumed items were valued in this way.

> 19 Forgotten items refer to the following. At the end of each of the 2 weeks of the three diary variants, the household is asked about the three main foods eaten daily and then the diary is reviewed to ensure that acquisition of these foods (including from stocks) are recorded. If these foods were omitted in the diary by mistake, the information is then collected by the enumerator (effectively in the form of recall).