es_from_md_se function

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

es_from_md_se(md, md_se, n_exp, n_nexp, smd_to_cor = "viechtbauer", reverse_md)

Arguments

• md: mean difference between two independent groups
• md_se: standard error 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 the standard error of a mean difference into a standard deviation:

$$inv\_n = \frac{1}{n\_exp} + \frac{1}{n\_nexp}$$ $$md\_sd = \frac{md\_se}{\sqrt{inv\_n}}$$

Calculations of the es_from_md_sd function are then used to estimate the Cohen's d and other effect size measures.

Examples

es_from_md_se(md = 4, md_se = 2, n_exp = 20, n_nexp = 22)

References

Higgins JPT, Li T, Deeks JJ (editors). Chapter 6: Choosing effect size measures and computing estimates of effect. In: Higgins JPT, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA (editors). Cochrane Handbook for Systematic Reviews of Interventions version 6.3 (updated February 2022). Cochrane, 2022. Available from www.training.cochrane.org/handbook.