Lost but Not Forgotten

Data from three waves of the Indonesian Family Life Survey (IFLS) are used to examine attrition in the context of a large scale panel survey conducted in a low income setting. Household-level attrition between the baseline and first follow-up four years later is 6%; the cumulative attrition between the baseline and second follow-up after a five year hiatus is 5%. Attrition is low in the IFLS because movers are followed: around 12% of households that were interviewed had moved from their location at baseline. About half of those households were "local movers". The other half, many of whom had moved to a new province, were interviewed during a second sweep through the study areas ("2nd stage tracking"). Regression analyses indicate that in terms of household-level characteristics at baseline, households interviewed during "2nd stage tracking" are very similar to those not interviewed in the follow-up surveys. Local movers are more similar to the households found in the baseline location in the follow-ups. The results suggest that the information content of households interviewed during "2nd tracking" is probably high. The costs of following those respondents is relatively modest in the IFLS. The authors conclude that tracking movers is likely to be a good investment in longitudinal households surveys conducted in settings where communication infrastructure is limited.