the household listing phase were intercropped at the time of the first interview, the final sample was made of up 385 pure stand maize plots and 515 intercropped maize plots (43 percent and 57 percent, respectively). Therefore, the sample comprises 900 maize plots, each one from a different household.

The MAPS fieldwork was implemented by the Uganda Bureau of Statistics, with technical and training support from the World Bank Living Standards Measurement Study (LSMS). Each household was visited three times for a post-planting interview, a crop cutting visit, and a postharvest interview. The post-planting visit involved the administration of a questionnaire and the GPS-based plot area measurements, the demarcation of crop-cutting subplots, and the collection of soil samples (discussed below) on the randomly selected maize plot. The post-planting questionnaire included a standard individual-level module on household composition and basic characteristics (age, gender, education, etc.), a durable assets module, a farming assets module, questions on the use and availability of agricultural extension services, and finally parcel and plotlevel details.<sup>8</sup> The plot-level modules made up the bulk of the post-planting questionnaire, with questions on tenure status, cultivation status, which household members manage the plot, what farm implements were used, what farm management practices were employed (for example, tillage, crop rotation, etc.), post-planting labor inputs, and most importantly, farmer assessment of plot area, soil quality, and seed usage. It is critical to note that farmer assessment was made _prior_ to any objective measurement so as to not influence the farmer response.<sup>9</sup> In the second visit, the crop-cutting visit, enumerators harvested the demarcated subplots which were set during the post-planting visit in order to obtain objectively measured production quantities for the crop-cutting subplots, which are subsequently extrapolated to the full plot area. The final household visit took place following completion of all maize harvests. At this time, farmers were administered an additional questionnaire, which asked for the estimated total maize production per plot as well as fertilizer inputs and harvest labor inputs.

> 8 Smallholder agricultural questionnaires in Uganda are structured such that there is a parcel of land, and within that parcel there may be multiple plots. The level of interest in this paper is the plot. In MAPS, a parcel was defined as “a contiguous piece of land with identical (uniform) tenure and physical characteristics. It is entirely surrounded by land with other tenure and/or physical characteristics or infrastructure e.g. water, a road, forest, etc.”  A plot was defined as “a contiguous piece of land within a parcel on which a specific crop or a crop mixture is grown. A parcel may be made up of one or more plots.”

> 9 Because MAPS was a small-scale methodological validation study, great care was taken to ensure that there were no missing values for the key variables, therefore, there are no concerns of missing data. There were, however, circumstances that required the sample to be restricted to 840 from 900. Plots which did not have any soil fertility measurement (due to mismatching of soil sample labels) or no crop-cutting (due to non-compliance of households) are excluded. The missingness of soil measurement is likely independent of production on the plot as the missingness stems from errors by the enumerator or laboratory. It could be argued, however, that non-compliance by the household (in which they harvest the crop-cutting subplot before the enumerator’s arrival) could be a systematic problem in which households with fewer resources cannot afford to forgo the maize on the crop-cutting subplot.

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