Bootstrap confidence interval for Cramer's V

Percentile bootstrap for the association strength in a contingency table. The table is expanded back to individual observations, which are resampled jointly. For a 2 by 2 table the statistic equals phi.

Usage

cramers_v_ci(tab, R = 2000, conf.level = 0.95, seed = NULL)

Arguments

tab

A contingency table (from table()) or a matrix of counts.

R

Integer. Number of bootstrap resamples. Defaults to 2000.

conf.level

Confidence level. Defaults to 0.95.

seed

Integer or NULL. When supplied, sets the random seed.

Value

A named numeric vector: estimate, lower, upper, with attributes resamples, valid_resamples and, when the interval is withheld, reason. The bounds are NA when fewer than 90% of resamples give a value, or when every resample gives the same value, since neither leaves a sampling distribution to read. The bounds are NA when the table holds fewer than 3 observations.

See also

bootstrap_ci()

Examples

cramers_v_ci(table(mtcars$am, mtcars$cyl), seed = 42)
#>  estimate     lower     upper 
#> 0.5226355 0.2581670 0.8157627 
#> attr(,"resamples")
#> [1] 2000
#> attr(,"valid_resamples")
#> [1] 1998