Performance of weighted estimating equations for longitudinal binary data with drop-outs missing at random |
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Authors: | Preisser John S Lohman Kurt K Rathouz Paul J |
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Institution: | Department of Biostatistics, CB #7420, School of Public Health, University of North Carolina, Chapel Hill 27599, USA. jpreisse@bios.unc.edu |
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Abstract: | The generalized estimating equations (GEE) approach is commonly used to model incomplete longitudinal binary data. When drop-outs are missing at random through dependence on observed responses (MAR), GEE may give biased parameter estimates in the model for the marginal means. A weighted estimating equations approach gives consistent estimation under MAR when the drop-out mechanism is correctly specified. In this approach, observations or person-visits are weighted inversely proportional to their probability of being observed. Using a simulation study, we compare the performance of unweighted and weighted GEE in models for time-specific means of a repeated binary response with MAR drop-outs. Weighted GEE resulted in smaller finite sample bias than GEE. However, when the drop-out model was misspecified, weighted GEE sometimes performed worse than GEE. Weighted GEE with observation-level weights gave more efficient estimates than a weighted GEE procedure with cluster-level weights. |
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Keywords: | correlated data drop‐outs estimating equations logistic models repeated measures |
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