Conversion from Means and Standard Deviations to Cohen's d

Helper function to convert means and standard deviations to Cohen's d.

means.to.d(mu1, mu2 = 0,
           sd1 = 1, sd2 = 1,
           n2, n.ratio = 1,
           paired = FALSE,
           rho.paired = 0.50,
           verbose = TRUE)

Arguments

mu1: mean of the first group.
mu2: mean of the second group.
sd1: standard deviation of the first group.
sd2: standard deviation of the second group.
n.ratio: n1/n2 ratio (applies to independent samples only).
paired: if TRUE paired samples
rho.paired: correlation between repeated measures for paired samples (e.g., pretest and post-test).
n2: integer; sample size in the second group (or for the single group in paired samples).
verbose: logical; whether the output should be printed on the console. TRUE by default.

Value

d: Cohen's d

Examples


# means and standard deviations from independent samples
means.to.d(mu1 = 20, mu2 = 17.5,
           sd1 = 5, sd2 = 15,
           n2 = 30, n.ratio = 1)
#> Warning: Interpretation of Cohen's d may no longer be valid when variances differ beyond sampling error.
#>         d 
#> 0.2236068 

# means and standard deviations from paired samples
means.to.d(mu1 = 20, mu2 = 17.5,
           sd1 = 5, sd2 = 15,
           n2 = 30, n.ratio = 1,
           paired = TRUE,
           rho.paired = 0.50)
#> Warning: Interpretation of Cohen's d may no longer be valid when variances differ beyond sampling error.
#>         d 
#> 0.1889822