

   NNooddaall IInnvvoollvveemmeenntt iinn PPrroossttaattee CCaanncceerr

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

          m: A column of ones.

          r: An indicator of nodal involvement.

       aged: The patients age dichotomized into less than 60
             (`0') and 60 or over `1'.

      stage: A measurement of the size and position of the
             tumour observed by palpatation with the fingers
             via the rectum.  A value of `1' indicates a more
             serious case of the cancer.

      grade: Another indicator of the seriousness of the can-
             cer, this one is determined by a pathology reading
             of a biopsy taken by needle before surgery.  A
             value of `1' indicates a more serious case of the
             cancer.

       xray: A third measure of the seriousness of the cancer
             taken from an X-ray reading.  A value of `1' indi-
             cates a more serious case of the cancer.

       acid: The level of acid phosphatase in the blood serum.

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

        The `nodal' data frame has 53 rows and 7 columns.

        The treatment strategy for a patient diagnosed with
        cancer of the prostate depend highly on whether the
        cancer has spread to the surrounding lymph nodes.  It
        is common to operate on the patient to get samples from
        the nodes which can then be analysed under a microscope
        but clearly it would be preferable if an accurate
        assessment of nodal involvement could be made without
        surgery.

        For a sample of 53 prostate cancer patients, a number
        of possible predictor variables were measured before
        surgery.  The patients then had surgery to determine
        nodal involvement.  It was required to see if nodal
        involvement could be accurately predicted from the pre-
        dictor variables and which ones were most important.

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

        This data frame contains the following columns:

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

        The data were obtained from

        Brown, B.W. (1980) Prediction analysis for binary data.
        In Biostatistics Casebook.  R.G. Miller, B. Efron, B.W.
        Brown and L.E. Moses (editors), 3-18. John Wiley.

   OOTTHHEERR RREEFFEERREENNCCEESS::

        Davison, A.C. and Hinkley, D.V. (1997) Bootstrap Meth-
        ods and Their Application. Cambridge University Press.

