Data of the locations of 761 cases of primary biliary cirrhosis in several
adjacent health regions of north-eastern England, along with 3020 controls
representing the at-risk population, collected between 1987 and 1994. These
data were first presented and analysed by Prince et al. (2001); subsequent
analysis of these data in the spirit of sparr was performed in
Davies and Hazelton (2010). Also included is the polygonal study region.
Format
pbc is a dichotomously marked
ppp.object, with locations expressed in UK Ordnance
Survey Coordinates (km).
Source
Prince et al. (2001), The geographical distribution of primary biliary cirrhosis in a well-defined cohort, Hepatology, 34, 1083-1088.
Acknowledgements
The authors thank Prof. Peter Diggle for providing access to these data.
References
Davies, T.M. and Hazelton, M.L. (2010), Adaptive kernel estimation of spatial relative risk, Statistics in Medicine, 29(23) 2423-2437.
Examples
data(pbc)
summary(pbc)
#> Marked planar point pattern: 3781 points
#> Average intensity 0.4706298 points per square km
#>
#> *Pattern contains duplicated points*
#>
#> Coordinates are given to 1 decimal place
#> i.e. rounded to the nearest multiple of 0.1 km
#>
#> Multitype:
#> frequency proportion intensity
#> case 761 0.2012695 0.09472343
#> control 3020 0.7987305 0.37590640
#>
#> Window: polygonal boundary
#> single connected closed polygon with 115 vertices
#> enclosing rectangle: [356.034, 447.701] x [506.395, 661.709] km
#> (91.67 x 155.3 km)
#> Window area = 8033.92 square km
#> Unit of length: 1 km
#> Fraction of frame area: 0.564
plot(pbc)
