calculating length of the land modules for individuals who own land versus those with no land). We are also able to provide estimates on the extent to which interview length for sampled households rises with the number of household adult members targeted for individual interviews. On average, having one additional interview with an adult household member increases total household interview time by about 37 to 48 minutes in Cambodia. In Ethiopia, this number is 41 minutes when moving from one targeted individual to two, then shifts to less than 22 minutes per any additional individual interview target. Tanzania’s increase in additional time per interview target is the largest relative to other countries, given the number of modules the survey administered (as high as 191 minutes and as low as 81 minutes).

Furthermore, the analysis combines the duration data with the information on the total survey costs to provide the cost estimate for a minute of face-to-face multi-topic survey data collection in each country. In Cambodia, the cost per minute is estimated at $0.87, while the comparable figures are $1.71 in Ethiopia, and $3.94 in Tanzania. These cost estimates can be used to construct budgets for hypothetical surveys in comparable country contexts, as a function of the expected total interview time per household, which would be mediated by the estimated duration of specific questionnaire modules (which can be informed by this paper) and the number of intra-household interview targets (in the case of individual-level data collection). We posit the unit costs reported in this paper to be more informative and comparable than the past cross-country cost estimates per interviewed household (see, for example, Kilic et al. 2017) since the countries differ significantly in terms of the approach to and scope of household survey data collection.

Subsequently, we turn to the cross-country analysis of interviewer effects on module duration. Interviewers play a large part in survey implementation, with potential effects on how respondents answer questions, non-response, measurement errors, and interview length (West and Blom 2017; Flores-Macias et al. 2008; Vollmer et al. 2021; Maio and Fiala 2020). Regarding interviewer effects on interview length, past research has focused exclusively on high-income settings (Couper and Kreuter, 2013). Contributing to this literature, we rely on multi-level hierarchical models of module duration, with levels defined as enumeration areas and interviewers; compute the interclass correlation coefficient (ICC) for each module, under different model specifications; and decompose the ICC to understand the extent of the variance in module duration that is explained by its interviewer component (i.e., ICC-I).

Our findings show that interviewer effects vary by module, despite having the same interviewer sample across modules. These effects are generally higher relative to the comparable multi-level model estimates from high-income countries and explain a large share of the total variance in interview length. Based on our preferred multi-level hierarchical module specification, interviewer effects explain 2 to 50 percent of total variance, depending on the module and country.

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