R: Cohen's Effect Size

CohenD {DescTools} | R Documentation

## Cohen's Effect Size

### Description

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

### Usage

    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

    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)

[Package DescTools version 0.99.32 Index]