cohens_d_unpaired: Compute Cohen's d

In markushuff/PsychHelperFunctions: Common helper functions for psychological data analysis

Compute Cohen's d

Description

Pustejovsky (2014) states for sample sizes using an unpaired t-test with sample sizes n1 and n2 Cohen's d = t [Sqrt(1/n1 + 1/n2)] When n1 = n2 Cohen's d = 2t / Sqrt(df) (See Rosenthal (1994) and Howell (2013), p.649). This formula is used to compute Cohen's d from a t ratio via the cohens_d_unpaired function.

Usage

cohens_d_unpaired(t, n1, n2)

Arguments

t	t-value of unpaired t-test
n1	sample size group 1
n2	sample size group 2

Value

Cohen's d

References

http://imaging.mrc-cbu.cam.ac.uk/statswiki/FAQ/td

Howell, D. C. (2013) Statistical methods for psychologists. 8th Edition. International Edition. Wadsworth:Belmont, CA.

Pustejovsky, J. E. (2014) Converting from d to r to z when the design uses extreme groups, dichotomization, or experimental control. Psychological Methods 19(1) 92-112.

Rosenthal, R. (1994) Parametric measures of effect size. In H. Cooper and L.V. Hedges (Eds.). The handbook of research synthesis. New York: Russell Sage Foundation.

markushuff/PsychHelperFunctions documentation built on Sept. 11, 2022, 3:43 a.m.