Jin Wang had an error. My original note specified a variable that was 1 for
subjects NOT in the subcohort, so the correct coxph call is
coxph(Surv(edrel, rel) ~ stage + histol + age +
offset(-100*(subcohort==0)) + cluster(seqno), data =ccoh.data)
This gives the same coefficients as the cch example, along with the
infinitesimal jackknife or "robust" variance estimate.
Terry Therneau
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