Abstract
Two robust methods for the analysis of longitudinal data are discussed. The marginal linear model with correlated observations within individuals is employed. We summarize literature on robust methods and suggest the modifications of Huggins' and Jung's estimates to simplify the procedure for the analysis of longitudinal data. The small sample behaviours of the two estimates are investigated under various situations by simulation. A real data set is analysed. This paper provides a useful reference for practitioners to the choice of robust methods in the analysis of longitudinal data.
