esvis (version 0.3.1)

v: Calculate the V effect size statistic

Description

This function calculates the effect size V, as discussed by Ho, 2009. The V statistic is a transformation of auc, interpreted as the average difference between the distributions in standard deviation units.

Usage

v(data, formula, ref_group = NULL)

Arguments

data

The data frame used for estimation - ideally structured in a tidy format.

formula

A formula of the type out ~ group where out is the outcome variable and group is the grouping variable. Note this variable can include any arbitrary number of groups. Additional variables can be included with + to produce separate estimates by the secondary or tertiary variables of interest (e.g., out ~ group + characteristic1 + characteristic2).

ref_group

Optional. A character vector or forumla listing the reference group levels for each variable on the right hand side of the formula, supplied in the same order as the formula. Note that if using the formula version, levels that are numbers, or include hyphens, spaces, etc., should be wrapped in back ticks (e.g., ref_group = ~ Active + `Non-FRL`, or ref_group = ~`8`). When in doubt, it is safest to use the back ticks, as they will not interfere with anything if they are not needed. See examples below for more details.

Value

By default the V statistic for all possible pairings of the grouping factor are returned as a tidy data frame. Alternatively, a vector can be returned, and/or only the V corresponding to a specific reference group can be returned.

Examples

# NOT RUN {
# Calculate V for all pairwise comparisons
v(star, reading ~ condition) 

# Report only relative to regular-sized classrooms
v(star, 
    reading ~ condition, 
    ref_group = "reg")

# Report by ELL and FRL groups for each season, compare to non-ELL students
# who were not eligible for free or reduced price lunch in the fall (using
# the formula interface for reference group referencing).

# }
# NOT RUN {
v(benchmarks, 
      math ~ ell + frl + season,
      ref_group = ~`Non-ELL` + `Non-FRL` + Fall)

# Same thing but with character vector supplied, rather than a formula
v(benchmarks, 
      math ~ ell + frl + season,
      ref_group = c("Non-ELL", "Non-FRL", "Fall"))
# }
# NOT RUN {
# }