redist (version 4.2.0)

redist.dist.pop.overlap: Compare the Population Overlap Across Plans at the District Level

Description

This implements Crespin's 2005 measure of district continuity, as applied to the geographies represented by a plan, typically precincts or voting districts. This implementation assumes none of the precincts in plan_old or plan_new are split.

Usage

redist.dist.pop.overlap(plan_old, plan_new, total_pop, normalize_rows = TRUE)

Value

matrix with length(unique(plan_old)) rows and length(unique(plan_new)) columns

Arguments

plan_old

The reference or original plan to compare against

plan_new

The new plan to compare to the reference plan

total_pop

The total population by precinct This can also take a redist_map object and will use the population in that object. If nothing is provided, it weights all entries in plan equally.

normalize_rows

Default TRUE. Normalize populations by row. If FALSE, normalizes by column. If NULL, does not normalize.

References

"Using Geographic Information Systems to Measure District Change, 2000-02", Michael Crespin, Political Analysis (2005) 13(3): 253-260

Examples

set.seed(5)
data(iowa)
iowa_map <- redist_map(iowa, total_pop = pop, pop_tol = 0.01, ndists = 4)
plans <- redist_smc(iowa_map, 2)
plans_mat <- get_plans_matrix(plans)
ov <- redist.dist.pop.overlap(plans_mat[, 1], plans_mat[, 2], iowa_map)
round(ov, 2)

ov_col <- redist.dist.pop.overlap(plans_mat[, 1], plans_mat[, 2], iowa_map, normalize_rows = FALSE)
round(ov_col, 2)

ov_un_norm <- redist.dist.pop.overlap(plans_mat[, 1], plans_mat[, 2],
    iowa_map, normalize_rows = NULL)
round(ov_un_norm, 2)

iowa_map_5 <- iowa_map <- redist_map(iowa, total_pop = pop, pop_tol = 0.01, ndists = 5)
plan_5 <- get_plans_matrix(redist_smc(iowa_map_5, 1))
ov4_5 <- redist.dist.pop.overlap(plans_mat[, 1], plan_5, iowa_map)
round(ov4_5, 2)