cohen.ES: Conventional effects size

In pwr: Basic Functions for Power Analysis

Description

Give the conventional effect size (small, medium, large) for the tests available in this package

Usage

cohen.ES(test = c("p", "t", "r", "anov", "chisq", "f2"),
    size = c("small", "medium", "large"))

Arguments

test	The statistical test of interest
size	The ES : small, medium of large?

Value

The corresponding effect size

Author(s)

Stephane CHAMPELY

References

Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd ed.). Hillsdale,NJ: Lawrence Erlbaum.

Examples

## medium effect size for the correlation test
cohen.ES(test="r", size="medium")

## sample size for a medium size effect in the two-sided correlation test
## using the conventional power of 0.80
pwr.r.test(r=cohen.ES(test="r",size="medium")$effect.size,
  power=0.80, sig.level=0.05, alternative="two.sided")

Example output

     Conventional effect size from Cohen (1982) 

           test = r
           size = medium
    effect.size = 0.3


     approximate correlation power calculation (arctangh transformation) 

              n = 84.07364
              r = 0.3
      sig.level = 0.05
          power = 0.8
    alternative = two.sided

pwr documentation built on March 17, 2020, 5:11 p.m.