Imputation of non-ignorable nonresponses for income: analysis of a panel study on Taiwan

In this paper, the two-step generalized estimating equations (GEE) approach developed by Wang and Fitzmaurice (Biom J 2:302–318, 2006) is employed to handle income non-responses in the Panel Study of Family Dynamics survey conducted in Taiwan. In our analysis, we first construct a conditional logit model of the paid work equation by taking the missing patterns into account. We then use the estimation results to impute whether or not the nonresponses were working for pay. For those who were imputed or observed to work for pay, we adopt the two-step GEE method to estimate the income equation. Compared to simply deleting the missing cases, the two-step imputation procedure is found to improve the estimation results.