root crop production. Second, within the diary domain, we further assess the relative accuracy of both options, and the scale-up feasibility of the daily diary keeping with supervisory phone calls. These insights are relevant also for the set-up of mobile phone-based data collection platforms that aim to collect broader data from human subjects at higher frequency. Third, we compare the annual cassava yield estimates obtained under the four survey treatments to the household-specific annual crop cutting-based cassava yield estimates obtained by extrapolating the crop cut sub-plot yields to the entire household area under cassava cultivation. The discussion of the interrelationships among the different yield estimates within our study, as well as their comparisons to the referenced cassava yields at the national- and international-levels, present a sobering need for convergence on a common understanding of what widely-varying cassava yields capture. Finally, this is the first comprehensive study undertaken on the topic in Malawi; a country in which the food security role of cassava cannot be underestimated in the face of intensifying extreme weather events that have adversely affected seasonal agricultural production in the recent past. Our study spans five districts across all three regions of Malawi. The selected districts exhibit remarkable differences in terms of the extent to which cassava production is geared towards home consumption versus market sales; the length of the cassava harvest period (and varieties); and the plot-level intensity of cassava cultivation (in part depending on whether cassava is intercropped with other seasonal crops).

Under the assumption that true cassava production is underestimated due to incomplete recordkeeping even in diaries that are implemented over an extended period, the analysis reveals that compared to D1, the annual household cassava production was 295 kilograms higher, on average, under D2, corresponding to 28 percent of the D1 mean, and that the traditional gold standard is outperformed by a competing diary variant in terms of capturing cassava production as comprehensively as possible. Further, we document that the average difference between R1- and D1-based estimates was not statistically significant, but that R2 – the most cost-effective practice in large-scale surveys – underestimated annual production, on average, by 221 and 516 kilograms, compared to D1 and D2, respectively. And while both recall variants underestimated annual production by a significant margin compared to D2, R1 did so to a lesser extent.

Finally, compared to crop cutting – which is the traditional gold standard for _seasonal_ crop yield measurement and should be understood as an upper bound for _extended-harvest_ crop yield realized on the farm, the average household-level annual cassava yields (kilograms per hectare) were underestimated by each survey treatment – ranging from an underestimation of 25 percent under D2 to 47 percent under R2 – as expected and described below. Yet, the latest available average national cassava yield estimates from FAOSTAT and the Malawi Ministry of Agriculture, Irrigation and Water Development (MoAIWD) were at least twice as much as the average crop cutting-based annual cassava yield estimate across our study districts.

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