OasisR (version 2.0.0)

Eta2: A function to compute adjusted isolation index (Eta2)

Description

The adjusted isolation index is the standardized version of the isolation index, xPx, which controls for the effect of total population structure. Using the approximate version of xPx, the adjusted index is equal to Eta2 (the square of the correlation ratio) which, in the case of the binomial variable, is identical to the square of the mean square contingency coefficient phi. It can be used as a segregation score and varies from 0 (minimum segregation) to 1 (maximum segregation).

Usage

Eta2(x)

Arguments

x

- an object of class matrix (or which can be coerced to that class), where each column represents the distribution of a population group, within spatial units. The number of columns should be greater than 1 (at least 2 population groups are required). You should not include a column with total population in each unit, because this will be interpreted as a group.

Value

a numeric vector containing the adjusted isolation index value for each population group

References

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

Duncan O. D. and Duncan B. (1955) Residential Distribution and Occupational Stratification.. American Journal of Sociology 60 (5), pp. 493-503

See Also

Isolation indices: xPx, DPxx

Interaction indices: xPy, DPxy

Examples

x <- segdata@data[ ,1:2]
Eta2(x)