

   CCaarr SSppeeeeddiinngg aanndd WWaarrnniinngg SSiiggnnss..

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

      speed: Speeds of cars (in miles per hour).

     period: A numeric column indicating the time that the
             reading was taken.  A value of 1 indicates a read-
             ing taken before the sign was erected, a 2 indi-
             cates a reading taken shortly after erection of
             the sign and a 3 indicates a reading taken after
             the sign had been in place for some time.

    warning: A numeric column indicating whether the location
             of the reading was chosen to have a warning sign
             erected. A value of 1 indicates presence of a sign
             and a value of 2 indicates that no sign was
             erected.

       pair: A numeric column giving the pair number at which
             the reading was taken. Pairs were numbered from 1
             to 14.

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

        The `amis' data frame has 8437 rows and 4 columns.

        In a study into the effect that warning signs have on
        speeding patterns, Cambridgeshire County Council con-
        sidered 14 pairs of locations.  The locations were
        paired to account for factors such as traffic volume
        and type of road.  One site in each pair had a sign
        erected warning of the dangers of speeding and asking
        drivers to slow down.  No action was taken at the sec-
        ond site.  Three sets of measurements were taken at
        each site.  Each set of measurements was nominally of
        the speeds of 100 cars but not all sites have exactly
        100 measurements. These speed measurements were taken
        before the erection of the sign, shortly after the
        erection of the sign, and again after the sign had been
        in place for some time.

   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 kindly made available by Mr. Graham Amis,
        Cambridgeshire County Council, U.K.

   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.

