# CohenD: Cohen's Effect Size In AndriSignorell/DescTools: Tools for Descriptive Statistics

## Description

Computes the Cohen's d and Hedges'g effect size statistics.

## Usage

 `1` ```CohenD(x, y = NULL, pooled = TRUE, correct = FALSE, conf.level = NA, na.rm = FALSE) ```

## Arguments

 `x` a (non-empty) numeric vector of data values. `y` a (non-empty) numeric vector of data values. `pooled` logical, indicating whether compute pooled standard deviation or the whole sample standard deviation. Default is TRUE. `correct` logical, indicating whether to apply the Hedges correction. (Default: FALSE) `conf.level` confidence level of the interval. Set this to NA, if no confidence intervals should be calculated. (This is the default) `na.rm` logical. Should missing values be removed? Defaults to FALSE.

## Value

a numeric vector with 3 elements:

 `d` the effect size d `lwr.ci` lower bound of the confidence interval `upr.ci` upper bound of the confidence interval

## Author(s)

Andri Signorell <andri@signorell.net>

## References

Cohen, J. (1988) Statistical power analysis for the behavioral sciences (2nd ed.) Academic Press, New York.

Hedges, L. V. & Olkin, I. (1985) Statistical methods for meta-analysis Academic Press, Orlando, FL

Smithson, M.J. (2003) Confidence Intervals, Quantitative Applications in the Social Sciences Series, No. 140. Thousand Oaks, CA: Sage. pp. 39-41

## See Also

`mean`, `var`

## Examples

 ```1 2 3 4``` ```x <- d.pizza\$price[d.pizza\$driver=="Carter"] y <- d.pizza\$price[d.pizza\$driver=="Miller"] CohenD(x, y, conf.level=0.95, na.rm=TRUE) ```

AndriSignorell/DescTools documentation built on April 8, 2021, 5:51 a.m.