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Exploring attrition bias: The case of the Khayelitsha panel study (2000-2004)

Year: 2006
Author: Magruder, Jeremy
Unit: ASRU
Journal: South African Journal of Economics
Volume: 74
Issue: 4
Pages: 769-781

Attrition bias is a problem for users of panel data. Researchers need to know what socio-economic factors are associated with attrition, and whether this is of relevance for the kind of analysis they want to conduct. This paper discusses attrition bias in the 2000/2004 Khayelitsha panel study. It shows that women, shack-dwellers and people living in smaller households are more likely to attrit, but that the impact of these variables on the probability of attrition is relatively small. The implications for labour-market analysis are then explored using Mincerian earnings functions and a probit regression on whether respondents are wage-employed or not. The coefficients generated using a restricted sample of non-attritors do not differ significantly from those generated by the entire sample. This suggests that attrition bias in this particular data set is not a problem for this kind of labour market analysis.

Keywords: attrition, Khayelitsha panel study, South Africa, Cape Town, attrition bias