Returns local segregation indices for each category defined by unit.

mutual_local(
  data,
  group,
  unit,
  weight = NULL,
  se = FALSE,
  CI = 0.95,
  n_bootstrap = 100,
  base = exp(1),
  wide = FALSE
)

Arguments

data

A data frame.

group

A categorical variable or a vector of variables contained in data. Defines the dimension over which segregation is computed.

unit

A categorical variable or a vector of variables contained in data. Defines the group for which local segregation indices are calculated.

weight

Numeric. (Default NULL)

se

If TRUE, the segregation estimates are bootstrapped to provide standard errors and to apply bias correction. The bias that is reported has already been applied to the estimates (i.e. the reported estimates are "debiased") (Default FALSE)

CI

If se = TRUE, compute the confidence (CI*100) in addition to the bootstrap standard error. This is based on percentiles of the bootstrap distribution, and a valid interpretation relies on a larger number of bootstrap iterations. (Default 0.95)

n_bootstrap

Number of bootstrap iterations. (Default 100)

base

Base of the logarithm that is used in the calculation. Defaults to the natural logarithm.

wide

Returns a wide dataframe instead of a long dataframe. (Default FALSE)

Value

Returns a data.table with two rows for each category defined by unit, for a total of 2*(number of units) rows. The column est contains two statistics that are provided for each unit: ls, the local segregation score, and

p, the proportion of the unit from the total number of cases. If se is set to TRUE, an additional column se contains the associated bootstrapped standard errors, an additional column CI contains the estimate confidence interval as a list column, an additional column bias contains the estimated bias, and the column est contains the bias-corrected estimates. If wide is set to TRUE, returns instead a wide dataframe, with one row for each unit, and the associated statistics in separate columns.

References

Henri Theil. 1971. Principles of Econometrics. New York: Wiley.

Ricardo Mora and Javier Ruiz-Castillo. 2011. "Entropy-based Segregation Indices". Sociological Methodology 41(1): 159–194.

Examples

# which schools are most segregated?
(localseg = mutual_local(schools00, "race", "school",
                         weight = "n", wide = TRUE))
#>       school        ls            p
#>    1:   A1_1 0.1826710 0.0004522985
#>    2:   A1_2 0.1825592 0.0004978701
#>    3:   A1_3 0.2756157 0.0006642066
#>    4:   A1_4 0.1368034 0.0005685061
#>    5:   A2_1 0.3585546 0.0004260948
#>   ---                              
#> 2041: C165_1 0.3174930 0.0004568556
#> 2042: C165_2 0.3835477 0.0005297702
#> 2043: C165_3 0.2972550 0.0005650883
#> 2044: C166_1 0.3072281 0.0011586588
#> 2045: C167_1 0.3166498 0.0005354667

sum(localseg$p) # => 1
#> [1] 1

# the sum of the weighted local segregation scores equals
# total segregation
sum(localseg$ls * localseg$p) # => .425
#> [1] 0.425539
mutual_total(schools00, "school", "race", weight = "n") # M => .425
#>    stat        est
#> 1:    M 0.42553898
#> 2:    H 0.05642991