household members who had worked on the plot during the previous week were identified, and the hours for each day they worked on the plot during the previous week were reported.<sup>9</sup>

- **_Weekly phone:_** _Weekly phone surveys for the duration of the masika_<sup>10</sup>

- For weekly phone households, a face-to-face baseline survey was conducted in January 2014 (during which households were provided with mobile phones to respond to subsequent surveys), followed by weekly phone surveys through the end of June 2014 and a face-to-face end line survey in July–September 2014 to collect farm production information. For each plot, household members who had worked on the plot during the previous week were identified, and the hours for each day they worked on the plot during the previous week were reported.

- **_Recall NPS:_** _Face-to-face survey at the end of the masika, standard NPS module_ For recall NPS households, a face-to-face end line survey was conducted after the harvest (July–September 2014), during which both labor and farm production information was collected. The agricultural labor module was identical to the respective module in the Tanzania NPS, waves 3 (2012/13) and 4 (2014/15). For each plot, the household members who worked the plot at any point during the season were identified, and the following information was reported: (a) total days spent on the plot over the season in each of four activities (land preparation and planting; weeding; ridging, fertilizer application, and other nonharvest activities; and harvesting) and (b) typical hours per day worked in each of these four activities.

- **_Recall alternative (ALT):_** _Face-to-face survey at the end of the masika, alternate survey module_

- For recall ALT households, a face-to-face end line survey was conducted after the harvest (July–September 2014), during which both labor and farm production information was collected. For each plot, the household members who had worked on that plot at any point during the season were identified, and the following information was reported: (a) total weeks worked on the plot over the season (irrespective of activity), (b) approximate number of days per week worked, and (c) approximate number of hours worked per day.

Throughout this paper, we establish the magnitude of bias through comparisons with the weekly visit design. This is based on the premise that the data reported in the weekly visit design are likely to be the closest to the actual situation given that weekly visit and weekly phone respondents were probed for day-by-day responses that were specific to the plot and to the person. Accordingly, these interviews minimized the need for respondents to make any complicated calculations or inferences regarding seasonwide labor. While we cannot exclude the possibility that forgetting or telescoping still led to some bias, we assume that the short one-week period and

> 9 In addition, after the hours per person per day over the previous week were reported, the range of activities performed during that time was recorded (land preparation and planting; weeding; ridging, fertilizer application, and other nonharvest activities; harvesting), but the number of hours were not specified for each activity.

> 10 The weekly phone interview design draws on lessons summarized by Dillon (2012), who uses a phone survey to collect information on purchased input applications among cotton farmers in Tanzania. Similar recent work has used phone surveys to collect high-frequency data on economic activity. See Garlick, Orkin, and Quinn (2015) for a review of the literature on phone-based strategies for collecting household and enterprise data.

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