While LFS, DHS and LSMS surveys typically visit each household only once, some LSMS‐ISA surveys visit each household twice administering the post‐planting questionnaire during the first and the post‐harvest questionnaire during the second visit. However, the labor module is generally only administered once. The exception is the 2015/16 Nigeria LSMS‐ISA survey that administers the labor module during both visits and, thus, allows to estimate the employment rate at two moments in the agricultural year.

The Malawi General Household Panel survey adopted a variant of this approach. Like other LSMS‐ISA surveys, each household is visited twice, and the labor module is only administered once. In contrast to other LSMS‐ISA surveys, the sample is randomly divided in two groups. The labor module is administered to the first group during the first visit and to the second group during the second visit. Hence, the employment rate can be estimated at two moments in time, while the labor module has only been administered once to each household. In this sense, this approach resembles a continuous survey. Results, not reported here, but available upon request, show that the employment rate is nearly the same in the post‐planting and post‐ harvest period, suggesting that seasonality is either not a major issue in Malawi or plays only a role in‐between the planting and harvesting period.

# 4.3.3. The reference period

The drawback of continuous surveys or surveys with multiple visits are the costs and the logistics required to implement them. For this reason, these types of surveys are often not feasible. An alternative approach is complementing the standard 7‐day reference period with a 12‐month reference period. While this strategy does not allow estimating the annual average employment rate – which relies on a 7‐day reference period ‐, it does provide some insights in the seasonality of labor demand and the occurrence of engaging in multiple economic activities throughout the year.

Since the 1980s and 1990s, several authors have supported the use of a 12‐month reference period (Freedman et al., 1977). Thus, the LSMS reference work suggested complementing the 7‐day reference period with a 12‐month reference period in order to capture seasonality and multiple jobs (Grosh & Glewwe, 2000, chapter 9). Follow‐up questions are then included for activities carried out in the last 7 days, but not for those carried out during the last 12 months. The idea is that respondents can accurately recall details about the activities of the last 7 days, but not of the last 12 months. Using two reference periods is now a standard practice, that has been adopted by DHS and by most LSMS(‐ISA) surveys. ILO, for instance, defines the _currently_ active population, which is measured over a day or a week, and the _usually_ active population, which is measured over a long reference period, such as one year (ILO, 2013c).

The main concern of the 12‐month reference period is recall error (Kalton & Schuman, 1982). Beegle et al. (2012) show that recall errors did not lead to an underestimation of hired farm labor in Kenya, Malawi, and Rwanda. Arthi et al. (2016) find, however, strong evidence of recall bias in agricultural labor input per person‐plot in Tanzania, but also show that labor input aggregated at household level yields correct results because respondents overreport labor‐ 17