

   SSuurrvviivvaall TTiimmeess aanndd WWhhiittee BBlloooodd CCoouunnttss ffoorr LLeeuukkaaeemmiiaa PPaattiieennttss

   AArrgguummeennttss::

        wbc: white blood count

         ag: a test result, `"present"' or `"absent"'

       time: survival time in weeks

   SSUUMMMMAARRYY::

        A data frame of data from 33 leukaemia patients.

   DDAATTAA DDEESSCCRRIIPPTTIIOONN::

        A data frame with columns:

   SSOOUURRCCEE::

        D.R. Cox and D. Oakes (1984) Analysis of Survival Data,
        Chapman  Hall, p. 9.  Taken from

        Feigl, P.  Zelen, M. (1965) Estimation of exponential
        survival probabilities with concomitant information.
        Biometrics, 21, 826-838.

   EExxaammpplleess::

        library(survival4)
        data(leuk)
        attach(leuk)
        plot(survfit(Surv(time) ~ ag), lty=c(2,3))

        # now Cox models
        leuk.cox <- coxph(Surv(time) ~ ag+log(wbc))
        summary(leuk.cox)

