On the relation between parameter estimates fromtransition and marginal models for longitudinal
نویسندگان
چکیده
Zeger and Liang (1992) allege that regression parameter estimates from transition models tend to be smaller in absolute value than regression parameter estimates from marginal models. This statement is true in typical longitudinal data situations for the relation between the true parameters of the marginal and transition model. However, under the assumption of a transition model the Generalized Estimating Equation (GEE) approach with a non-diagonal working correlation matrix may yield inconsistent estimates for the parameters of the marginal model. Hence the stated relation may be valid for the true parameters, but not for the stochastic limit of the parameter estimates.
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