es_from_md_sd function

Convert a mean difference between two independent groups and standard deviation into several effect size measures

es_from_md_sd(md, md_sd, n_exp, n_nexp, smd_to_cor = "viechtbauer", reverse_md)

Arguments

• md: mean difference between two independent groups
• md_sd: standard deviation of the mean difference
• n_exp: number of participants in the experimental/exposed group.
• n_nexp: number of participants in the non-experimental/non-exposed group.
• smd_to_cor: formula used to convert the cohen_d value into a coefficient correlation (see details).
• reverse_md: a logical value indicating whether the direction of generated effect sizes should be flipped.

Returns

This function estimates and converts between several effect size measures.

natural effect size measure	MD + D + G
converted effect size measure	OR + R + Z
required input data	See 'Section 10. Mean difference and dispersion (crude)'
	https://metaconvert.org/input.html

Details

This function converts the mean difference and 95% CI into a Cohen's d (D) and Hedges' g (G). Odds ratio (OR) and correlation coefficients (R/Z) are then converted from the Cohen's d.

The formula used to obtain the Cohen's d is:

$$d = \frac{md}{md\_sd}$$

Note that this formula is perfectly accurate only if the md_sd has been estimated by assuming that the variance of the two groups is equal.

To estimate other effect size measures , calculations of the es_from_cohen_d() are applied.

Examples

es_from_md_sd(md = 4, md_sd = 2, n_exp = 20, n_nexp = 22)