[R] Cox's regression analysis with Left truncated data

[Terry Therneau]

Surv(entry-time, last-follow-up-time, status-at-last-follow-up)
This works in survfit, coxph, and coxme.  Left truncation is currently
not implemented for survreg.
  In your case both times above would be "time since event".
Terry T.

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I have a fairly simple question.  I would like to use the survival
package
to perform an analysis on data where an event can have occurred before
individuals were recruited into a study.  I'm not sure how to do this
using
the Surv() function.  I would have a date of an event and then the
enrolment
date would be after that.  How do I put these two dates into the
survival
function?