program. In turn, we aggregated the kilogram-equivalent production across the cassava plots to obtain the household-level annual cassava production estimates.

If implemented with the intended level of supervision and respondent participation, diary-keeping is traditionally assumed to be the gold standard in data collection on production (Deininger et al., 2012) and on consumption (Beegle et al., 2012). However, as Beegle et al (2012) highlight, while well-implemented diaries are expected to yield higher and presumably closer to actual levels of consumption, the success of a diary operation is mediated by respondent literacy and motivation, as well as field staff effort, among others.P24F<sup>25</sup> Although CVIP attempted to circumvent respondent fatigue through incentives, and relied on highly-trained, -supervised, and -experienced enumerators and call center operators, given the prevalence of diary decay even in 7-day operations, we concede that omission of harvest records must have been unavoidable during the 12-month CVIP fieldwork. Therefore, while diary-keeping is still expected to underestimate _true_ production, it is assumed to (i) underestimate to a lesser degree compared to recall, and (ii) offer the best chance to capture annual cassava production as accurately as possible.

In terms of inter-relationships, D1 was set-up to be executed as well as any traditional diary-based field operation but given the long fieldwork duration and the potential respondent burden, imperfect compliance was expected, albeit to a limited degree. However, the D1 versus D2 comparison is not clear ex-ante. On the one hand, D2 could underestimate annual cassava production with respect to D1, given the lack of frequent personal interaction with a qualified enumerator, who would nudge for timely recording of harvests; help recall omitted harvests; and field questions. On the other hand, the degree of non-compliance could be more limited among the D2 respondents in comparison to their D1 counterparts, mainly due to the significantly more valuable set of incentives that they received to be part of CVIP.P25F<sup>26</sup> In comparison to the recall variants, both diary treatments are expected to reduce two main sources of bias that typically lead to underestimation of annual cassava production. First, since the harvest is captured immediately upon harvest, recall decay should be minimized. Second, diaries should reduce the scope for respondent bias that may arise with recall. Recall-based interviews are often conducted in a specific time frame that revolves less around the schedule of the ideal respondents (i.e. the plot managers) resulting in a greater potential for proxy reporting. Lastly, within the recall domain, it is possible that R1 reduces the scope for recall decay to a greater degree compared to R2, since the R1 respondents are asked to recall over 6, as opposed to 12, months.

> 25 A specific example of an unsuccessful diary effort is in fact from Malawi, with 40 percent of households in the First Integrated Household Survey (IHS1) 1997/98 having been judged to have incomplete or unreliable expenditure data due to poor diary-keeping.

> 26 This claim needs to be supported with the available empirical evidence on the impact of gifting on survey data quality.

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