Spatial locations of cases of childhood leukaemia and lymphoma, and randomly-selected controls, in North Humberside. A marked point pattern.
an object of class
representing a marked point pattern.
||Cartesian x-coordinate of home address|
||Cartesian y-coordinate of home address|
|| factor with levels
|indicating whether this is a disease case|
|or a control.|
ppp.object for details of the format.
humberside.convex is an object of the
same format, representing the same point pattern data,
but contained in a larger, 5-sided convex polygon.
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,
To remove the duplication, use
Two versions of the dataset are supplied, both containing the
same point coordinates, but using different windows.
humberside has a polygonal window with 102 edges
which closely approximates the Humberside region,
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.)
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).
J. Cuzick and R. Edwards (1990) Spatial clustering for inhomogeneous populations. Journal of the Royal Statistical Society, series B, 52 (1990) 73-104.
P.J. Diggle and A.G. Chetwynd (1991) Second-order analysis of spatial clustering for inhomogeneous populations. Biometrics 47 (1991) 1155-1163.
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