\name{humberside}
\alias{humberside}
\alias{humberside.convex}
\docType{data}
\title{Humberside Data on Childhood Leukaemia and Lymphoma}
\description{
  Spatial locations of cases of childhood leukaemia
  and lymphoma, and randomly-selected controls,
  in North Humberside.
  A marked point pattern.
} 
\format{
  The dataset \code{humberside} is
  an object of class \code{"ppp"}
  representing a marked point pattern.
  Entries include
  \tabular{ll}{
    \code{x} \tab Cartesian \eqn{x}-coordinate of home address \cr
    \code{y} \tab Cartesian \eqn{y}-coordinate of home address \cr
    \code{marks} \tab factor with levels \code{case} and \code{control} \cr
    \tab indicating whether this is a disease case\cr
    \tab or a control.
  }
  See \code{\link[spatstat]{ppp.object}} for details of the format.

  The dataset \code{humberside.convex} is an object of the
  same format, representing the same point pattern data,
  but contained in a larger, 5-sided convex polygon.
}
\usage{data(humberside)}
\examples{
  if(require(spatstat)) {
   humberside
   summary(humberside)
   plot(humberside)
   plot(Window(humberside.convex), add=TRUE, lty=2)
  }
}
\source{
  Dr Ray Cartwright and Dr Freda Alexander.
  Published and analysed in Cuzick and Edwards (1990), see Table 1.
  Pentagonal boundary from Diggle and Chetwynd (1991), Figure 1.
  Point coordinates and pentagonal boundary supplied by Andrew Lawson.
  Detailed region boundary was digitised by \adrian, 2005, from
  a reprint of Cuzick and Edwards (1990).
}
\section{Notes}{
  Cuzick and Edwards (1990) first presented and analysed these data.

  The data record 62 cases of childhood leukaemia and lymphoma
  diagnosed in the North Humberside region of England between 1974 and
  1986, together with 141 controls selected at random from the birth
  register for the same period.

  The data are represented as a marked point pattern,
  with the points giving the spatial location of each individual's home address
  (actually, the centroid for the postal code)
  and the marks identifying cases and controls.

  Coordinates are expressed in units of 100 metres, and the resolution is
  100 metres. At this resolution, there are some duplicated points.
  To determine which points are duplicates,
  use \code{\link[spatstat]{duplicated.ppp}}.
  To remove the duplication, use \code{\link[spatstat]{unique.ppp}}.
  
  Two versions of the dataset are supplied, both containing the
  same point coordinates, but using different windows.
  The dataset \code{humberside} has a polygonal window with 102 edges
  which closely approximates the Humberside region,
  while \code{humberside.convex} has a convex 5-sided polygonal window 
  originally used by Diggle and Chetwynd (1991) and shown in
  Figure 1 of that paper. (This pentagon has been modified slightly
  from the original data, by shifting two vertices horizontally by 1 unit,
  so that the pentagon contains all the data points.)
}
\references{
  J. Cuzick and R. Edwards (1990)
  Spatial clustering for inhomogeneous populations.
  \emph{Journal of the Royal Statistical Society, series B},
  \bold{52} (1990) 73-104.

  P.J. Diggle and A.G. Chetwynd (1991)
  Second-order analysis of spatial clustering for
  inhomogeneous populations. \emph{Biometrics} 47 (1991) 1155-1163.
} 
\keyword{datasets}
\keyword{spatial}

