gauge the potential direction of bias in different literature strands. Using the person-plot level as a starting point has two main advantages. First, to provide guidance to survey designers, it appears useful to assess recall bias directly at the unit at which the data are reported by the respondents. Second, this approach enables us to further disentangle the proximate causes of bias at higher levels of aggregation – i.e. incomplete listings of plots and household members (recall bias in listings or, simply, _listing bias_ – i.e. bias at the extensive margin) and recall bias in terms of days and hours of farm labor at the person-plot level, conditional on being listed (i.e. bias at the intensive margin).

# **2.3 Recall bias**

Most agricultural surveys ask respondents to report on farm labor over an extended reference period, such as the previous agricultural season. An example of this approach is the Tanzania NPS introduced in the previous section, which asked respondents to recall each household member’s labor input during the “long rainy season 2014”. The main advantage of using an extended reference period is that it minimizes the impact of seasonality and assures consistency between measures of farm labor and measures of seasonal crop production. This consistency is important when data on agricultural output are linked to data on family labor, for example to analyze agricultural labor or total factor productivity. The flip side of using an extended reference period is that it increases the burden on the respondent, by requiring them to recall events that occurred several months in the past and to perform complex mental calculations to arrive at averages.

Different cognitive processes suggest that recall bias may be linked to the length of recall period (see Arthi et al 2018 for further discussion). The most obvious explanation is a simple failure of memory, where respondents forget to report events that took place long ago. However, there is also evidence from cognitive research that the length of the recall period may have a bearing on how respondents interpret survey questions. Schwarz (2007), for example, shows that the longer the recall period, the more likely respondents are to interpret a given question as referring to major events only. This potential change in inferred meaning makes it difficult to distinguish between the effects of question interpretation and forgetting.

Several studies have found a positive association between the level of education – or direct measures of cognitive skills – and recall ability. Peters (1988), comparing lifecycle data from a retrospective marital history with panel reports for the same individuals in the United States, shows that more educated respondents report more consistently on marital events. McAuliffe, DiFranceisco and Reed (2010) find that arithmetic skills predict the accuracy of retrospective self-reports of sexual activity (also in the US). While evidence from the United States may not necessarily extend to developing countries, given potentially large differences in the quality of education systems, survey methods, etc., a few studies have found similar associations in Asia and Africa. Becket et al (1999, 2001) show that the reliability of reports in the Malaysian Family Life Surveys is higher for more educated respondents. Abebe (2013) finds that recall errors in sales revenues and output among Ethiopian shoemakers are negatively correlated with respondents’ years of schooling. Given this literature, we hypothesize that the accuracy of reports on farm labor is positively related to educational attainment, as a proxy for cognitive skills.

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