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

 CohenD 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

`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)

```

AndriSignorell/DescTools documentation built on Oct. 26, 2022, 10:30 a.m.