A colleague of mine is interested in using a discrete-time survival
analysis (not something I'm terribly familiar with) to analyze some data
of hers. Currently, her data include her predictors, dv (binary relapse
variable), and a weeks to relapse variable. It looks something like the
following:
id sex relapse weeks (there are other predictors besides sex)
1 male 0 4
2 male 1 2
3 female 1 3
4 female 0 4 (measured over a 4 week period)
She'd like to change her data frame to dummy code weeks and code the
relapse variable to be "positive" in the week they relapsed; so each
subject would have a number of rows equal to their weeks to relapse
variable. Something like:
id t1 t2 t3 t4 sex relapse
1 1 0 0 0 male 0
1 0 1 0 0 male 0
1 0 0 1 0 male 0
1 0 0 0 1 male 0
2 1 0 0 0 male 0
2 0 1 0 0 male 1
3 1 0 0 0 female 0
3 0 1 0 0 female 0
3 0 0 1 0 female 1...
Is there an splus function to transform the first data frame into the
second? (Hope that my explanation was clear enough).
thanks in advance,
Dave Atkins
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