I recently learned that the weight statement in proc logistic actually uses frequency weight, meaning a weight of 2 is equivalent to 2 independent observations in the analysis. I found it very bizarre. A regular generalized linear model does not deal with weights this way. It would treat the weight of 2 as a weight of 2 in the estimating equation instead of 2 independent observations. The glm() in R does so. When you use repeated statement with id variable in proc genmod, you would nullify this independent observation thing, and this makes a difference. I wonder in which scenario the frequency weight is useful for making inference. Could you clarify?
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