sd_pooled {effectsize}

Pooled Indices of (Co)Deviation

Description

The Pooled Standard Deviation is a weighted average of standard deviations for two or more groups, assumed to have equal variance. It represents the common deviation among the groups, around each of their respective means.

Usage

sd_pooled(x, y = NULL, data = NULL, verbose = TRUE, ...)

mad_pooled(x, y = NULL, data = NULL, constant = 1.4826, verbose = TRUE, ...)

cov_pooled(x, y = NULL, data = NULL, verbose = TRUE, ...)

Arguments

x, y

A numeric vector, or a character name of one in data. Any missing values (NAs) are dropped from the resulting vector. x can also be a formula (see stats::t.test()), in which case y is ignored.

data

An optional data frame containing the variables.

verbose

Toggle warnings and messages on or off.

...

Arguments passed to or from other methods. When x is a formula, these can be subset and na.action.

constant

scale factor.

Details

The standard version is calculated as:

\sqrt{\frac{\sum (x_i - \bar{x})^2}{n_1 + n_2 - 2}}

The robust version is calculated as:

1.4826 \times Median(|\left\{x - Median_x,\,y - Median_y\right\}|)

Value

Numeric, the pooled standard deviation. For cov_pooled() a matrix.

See Also

cohens_d(), mahalanobis_d()

Examples

sd_pooled(mpg ~ am, data = mtcars)
mad_pooled(mtcars$mpg, factor(mtcars$am))

cov_pooled(mpg + hp + cyl ~ am, data = mtcars)