This monograph extends previous work on the evaluation of GEE performance in parameter estimation with correlation structure misspecification. It examines a new structure to model the correlation between binary responses observed over unequal time intervals. The proposed unequal-time correlation structure accounts for unequal intervals by fixing the correlation coefficient and interval length between the first 2 observations and by adjusting the correlations for subsequent pairs by their relative interval length. To evaluate this structure, correlated binary responses under the logistic model...