Summary
Objective: To discuss generalized estimating equations as an extension of generalized linear
models by commenting on the paper of Ziegler and Vens “Generalized Estimating Equations:
Notes on the Choice of the Working Correlation Matrix”.
Methods: Inviting an international group of experts to comment on this paper.
Results: Several perspectives have been taken by the discussants. Econometricians have established
parallels to the generalized method of moments (GMM). Statisticians discussed model
assumptions and the aspect of missing data. Applied statisticians commented on practical
aspects in data analysis.
Conclusions: In general, careful modeling correlation is encouraged when considering estimation
efficiency and other implications, and a comparison of choosing instruments in GMM
and generalized estimating equations (GEE) would be worthwhile. Some theoretical drawbacks
of GEE need to be further addressed and require careful analysis of data. This particularly
applies to the situation when data are missing at random.
Keywords
Correlation matrix - generalized estimating equations - independence estimating equations
- restriction of parameter space