# cohens_d: Cohen's d In apa: Format Outputs of Statistical Tests According to APA Guidelines

## Description

Calculate Cohen's d from raw data or a call to `t_test`/`t.test`.

## Usage

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35``` ```cohens_d(...) ## Default S3 method: cohens_d( x, y = NULL, paired = FALSE, corr = c("none", "hedges_g", "glass_delta"), na.rm = FALSE, ... ) ## S3 method for class 'data.frame' cohens_d( data, dv, iv, paired = FALSE, corr = c("none", "hedges_g", "glass_delta"), na.rm = FALSE, ... ) ## S3 method for class 'formula' cohens_d( formula, data, paired = FALSE, corr = c("none", "hedges_g", "glass_delta"), na.rm = FALSE, ... ) ## S3 method for class 'htest' cohens_d(ttest, corr = c("none", "hedges_g", "glass_delta"), ...) ```

## Arguments

 `...` Further arguments passed to methods. `x` A (non-empty) numeric vector of data values. `y` An optional (non-empty) numeric vector of data values. `paired` A logical indicating whether Cohen's d should be calculated for a paired sample or two independent samples (default). Ignored when calculating Cohen's for one sample. `corr` Character specifying the correction applied to calculation of the effect size: `"none"` (default) returns Cohen's d, `"hedges_g"` applies Hedges correction and `"glass_delta"` calculates Glass' Δ (uses the standard deviation of the second group). `na.rm` Logical. Should missing values be removed? `data` A data frame containing either the variables in the formula `formula` or the variables specified by `dv` and `iv`. `dv` Character indicating the name of the column in `data` for the dependent variable `iv` Character indicating the name of the column in `data` for the independent variable `formula` A formula of the form `lhs ~ rhs` where `lhs` is a numeric variable giving the data values (dependent variable) and `rhs` a factor with two levels giving the corresponding groups (independent variable). `ttest` An object of class `htest` (a call to either `t_test` (preferred) or `t.test`).

## Details

To calculate Cohen's d from summary statistics (M, SD, ..) use cohens_d_.

## References

Lakens, D. (2013). Calculating and reporting effect sizes to facilitate cumulative science: a practical primer for t-tests and ANOVAs. Frontiers in Psychology, 4, 863. doi:10.3389/fpsyg.2013.00863

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12``` ```# Calculate from raw data cohens_d(c(10, 15, 11, 14, 17), c(22, 18, 23, 25, 20)) # Methods when working with data frames cohens_d(sleep, dv = extra, iv = group, paired = TRUE) # or cohens_d(sleep, dv = "extra", iv = "group", paired = TRUE) # formula interface cohens_d(extra ~ group, sleep, paired = TRUE) # Or pass a call to t_test or t.test cohens_d(t_test(extra ~ group, sleep, paired = TRUE)) ```

### Example output

``` -2.936071
 -1.284558
 -1.284558
 -1.284558
 -1.284558
```

apa documentation built on April 21, 2020, 5:05 p.m.