In each sampled EA, a household listing exercise was conducted to identify, separately, the list of households that were cultivating at least 1 pure stand maize plot, and the list of households that were cultivating at least 1 intercropped maize plot, on which maize is self-identified to be the dominant crop. Given the interest in the validation of survey methods in key sub-samples and the fact that approximately two-thirds of all maize plots are intercropped in Uganda, the original intention had been to select, at random, 6 households from each of the pure stand and intercropped universes of households of an EA, and ensure an even sample split by maize cultivation status.

Still, due to the low incidence of pure stand households, and the cases in which pure stand households would switch to intercropping status between the household listing and the first interview, the sample at the start of MAPS I fieldwork was composed of 900 households, of which 385 were pure stand (43 percent) and 515 were intercropped (57 percent). Within the remote sensing tasking area specifically, the MAPS I fieldwork started out with 540 households, of which 249 were pure stand (46 percent) and 291 (54 percent) were intercropped. In each MAPS household, 1 maize plot, matching the household cultivation status, was selected at random by the Survey Solutions CAPI application for crop cutting (for objective yield measurement) and soil sampling (for objective soil fertility analysis). The variety identification component was implemented among the 540 MAPS I households residing in the remote sensing tasking area (specific to the plots on which crop cutting and soil sampling took place), as explained below.

In MAPS II, the MAPS fieldwork was conducted during the first rainy season of 2016, from June to October 2016. The field teams attempted to track and re-interview 540 households that had been interviewed in MAPS I in the 400 km<sup>2</sup> remote sensing tasking area cutting across Iganga and Mayuge districts. Appendix I provides the MAPS II household tracking protocol that was followed by the field teams. The MAPS II fieldwork successfully interviewed 489 out of 540 households, and the sample informing our analyses is composed of 440 households for which we have obtained crop cutting measures in both rounds.<sup>10</sup> Further, as in Round I, 1 maize plot was selected from each household for crop cutting and variety identification components, in accordance with the following rules. Whenever possible, a plot was selected among those that were matching the household cultivation status in Round I. Preference was also given such that a plot would be selected from the same parcel that had contained the plot selected in Round I. If multiple plots match the household cultivation status, the CAPI application selected one plot at random. Appendix II lays out the MAPS II plot selection protocol that was implemented by the field teams.

> 10 34 out of 51 households that we did not interview in MAPS II were due to the fact that they were not cultivating maize in the first season of 2016. The remaining 17 households can be broken down as follows: 5 households could not be tracked or were outside of the tracking area defined as the Iganga and Mayuge districts (5); 4 households had suffered total crop loss prior to post-planting interview; 7 households had already harvested their maize by the postplanting interview; and 1 household refused. The final analysis sample of 440 households vis-à-vis the original 100 records that had at least been subject to the post-planting interview in MAPS I do not exhibit statistically significant differences in terms of their MAPS I yield measures and control variables for our regressions. The mean comparisons are available upon request. In line with this finding, our multivariate regressions are robust to the use of inverse predicted response probabilities in MAPS I as attrition weights.

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