Monday, October 8, 2007

 

Case Control Studies and Repeated Sampling

A standard counterintuitive result in statistics is that if the true model is logit, then it is okay to use a sample selected on the Y's, which is what the "case-control method" amounts to. You may select 1000 observations with Y=1 and 1000 observations with Y=0 and do estimation of the effects of every variable but the constant in the usual way, without any sort of weighting. This was shown in Prentice & Pyke (1979). They also purport to show that the standard errors may be computed in the usual way--- that is, using the curvature (2nd derivative) of the likelihood function. (Click here for more)

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