the standard household questionnaire in Visit 1 and had been administered the rest of the questionnaire in Visit 2.

The standard household questionnaire spanned 66 pages and 23 modules. Our experiment was administering an additional 2-page instrument (included in the Appendix), immediately after the household roster module (i.e. the first module following the cover page), to a subsample of IHPS households during the visit in which the interview would have only necessitated the administration of the household roster module. Toward this end, 4 households in each IHPS EA, out of the households that remained in the original EA between 2010 and 2013, were randomly selected for the experiment, and received the additional 2-page instrument. Since only households that had remained in the original EA were considered for the experiment, we limit the analysis sample to all households that remained in the original EA between 2010 and 2013, and that were subject to the two-visit approach in 2013.<sup>12</sup> This yields an analysis sample of 2,822 households, out of which 765 households were part of the experiment.<sup>13</sup> Table 1 provides an overview of the sample. Out of 1,428 Sample A households, who received the full standard questionnaire in Visit 1 and were revisited in Visit 2 for a household roster update, 393 households also received the additional 2-page instrument following the household roster module in Visit 2. Similarly, out of 1,394 Sample B households, who received only the household roster module in Visit 1 and the full standard questionnaire in Visit 2, 372 households were administered the additional 2-page instrument in Visit 1. Hence, 765 experiment records form a sub-sample of whom the same questions were asked in different questionnaires and at different points in time.

In selecting the questions to be included in the 2-page instrument for the experiment, we solicited inputs from the Statistics Norway staff that had supported the NSO in producing WMS-based poverty predictions, and aimed to (i) be able to compute the indicators from the Poverty Predictors module of the WMS questionnaire<sup>14</sup> , (ii) capture the poverty proxies used by past survey-to-survey imputation applications to the Malawi Second Integrated Household Survey (IHS2) 2004/05 data (Houssou & Zeller, 2011), and (iii) include other poverty proxies on food consumption, non-food consumption and subjective welfare that have been suggested in the literature but that are not currently used extensively (Christiaensen et al., 2012).

> 12 Given the demanding tracking objectives of the survey, the teams managed to implement the two-visit approach for 91.7 percent of the IHPS sample (i.e. 3,667 households). On average, there were 96 days between the two visits. 13 Table A1 in the Appendix presents the sample means for 36 household level attributes computed from the nonexperiment modules and the results from the tests of mean differences by whether a household was part of the experiment. No mean difference is statistically significant at least at the 10 percent level, supporting the view that on average, there are no systematic differences between the non-experiment and the experiment samples beyond the difference in the survey treatment that they were subject to randomly.

> 14 The Poverty Predictors module of the WMS questionnaire was unchanged during the period of 2005-2009, and also consisted of 2 pages.

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