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st: Data management question


From   "David J. Tucker" <celdjt@umich.edu>
To   statalist@hsphsun2.harvard.edu
Subject   st: Data management question
Date   Sun, 21 Jul 2002 15:16:22 -0400

I am new to stata so hope this question is not too naive. I am working with a file containing a mix of cases, some with single observations, others with multiple observations. Overall file has approx. 3600 cases with over 15500 observations. My plan is to model these data using survival analysis techniques. Generally I am exploring predictions about how the probability of a given type of change is influenced by elapsed time since a prior change of the same type. However, when I attempt to set up the data using snapspan, I end up with almost complete missing data (excepting for id value and failure indicator) for cases with single observations as well as for the first record in cases with multiple observations. Is there away to correct this, or to avoid having it happen? The replace missing values protocol does not work for the single observations cases, and generally is not adequate for first record in cases with multiple observations for various reasons. e.g., it drops one value from a cumulative frequency variable and throws off the appropriate alignment for time-varying covariates. Thanks in advance for any suggestions.

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