xPx: A function to compute Bell's isolation index (xPx)

In OasisR: Outright Tool for the Analysis of Spatial Inequalities and Segregation

A function to compute Bell's isolation index (xPx)

Description

The isolation index, xPx, is an exposure index that measures the probability that two members of a group share the same spatial unit. This index can be calculated using the approximate or the exact method (see Bell, 1954).

Usage

xPx(x, exact = FALSE)

Arguments

x	- an object of class matrix (or which can be coerced to that class), where each column represents the distribution of a group within spatial units. The number of columns should be greater than 1 (at least 2 groups are required). You should not include a column with total population, because this will be interpreted as a group.
exact	- a logical variable to specifiy the index version: exact = FALSE (by default) for the approximate version of the index, and exact = TRUE for the exact version

Value

a numeric vector containing the isolation index value for each group

References

Bell W. (1954) A probability model for the measurement of ecological segregation. Social Forces 32(4), pp. 357-364

See Also

Isolation indices: Eta2, DPxx

Interaction indices: xPy, DPxy

Examples

x <- segdata@data[ ,7:8]
xPx(x) 
xPx(x, exact = TRUE)

OasisR documentation built on Aug. 30, 2023, 1:09 a.m.