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Re: FW: st: Random effects probit
Daniel Müller <email@example.com> wrote:
Ooops, sorry about that. Here it is:
could you pls add the Stata answer you mention in your post on missing std
In general, it means that the standard error could not be identified.
way of saying the same thing is that the variance-covariance matrix does not
have full rank. collinearity is the most common cause. The fact that the
problem arises when you cl uster is not surprising. If you think of clusters
as superobservations, clustering can drastically reduce the rank of your
matrix (design matrix), i.e., in reality you have fewer observations, you
drastically reduce the overall variation in your data , making collinearity
more likely to be present.
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