es_from_mean_change_sd function

Convert mean changes and standard deviations of two independent groups into standard effect size measures

es_from_mean_change_sd(
  mean_change_exp,
  mean_change_sd_exp,
  mean_change_nexp,
  mean_change_sd_nexp,
  r_pre_post_exp,
  r_pre_post_nexp,
  n_exp,
  n_nexp,
  smd_to_cor = "viechtbauer",
  reverse_mean_change
)

Arguments

• mean_change_exp: mean change of participants in the experimental/exposed group.
• mean_change_sd_exp: standard deviation of the mean change for participants in the experimental/exposed group.
• mean_change_nexp: mean change of participants in the non-experimental/non-exposed group.
• mean_change_sd_nexp: standard deviation of the mean change for participants in the non-experimental/non-exposed group.
• r_pre_post_exp: pre-post correlation in the experimental/exposed group
• r_pre_post_nexp: pre-post correlation in the non-experimental/non-exposed group
• 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_mean_change: 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 14. Paired: mean change, and dispersion'
	https://metaconvert.org/input.html

Details

This function first computes a Cohen's d (D), Hedges' g (G) from the mean change (MC) and standard deviations of two independent groups. Odds ratio (OR) and correlation coefficients (R/Z) are then converted from the Cohen's d.

This function simply internally calls the es_from_means_sd_pre_post function but setting:

$$mean\_pre\_exp = mean\_change\_exp$$ $$mean\_pre\_sd\_exp = mean\_change\_sd\_exp$$ $$mean\_exp = 0$$ $$mean\_sd\_exp = 0$$ $$mean\_pre\_nexp = mean\_change\_nexp$$ $$mean\_pre\_sd\_nexp = mean\_change\_sd\_nexp$$ $$mean\_nexp = 0$$ $$mean\_sd\_nexp = 0$$

To know more about the calculations, see es_from_means_sd_pre_post function.

Examples

es_from_mean_change_sd(
  n_exp = 36, n_nexp = 35,
  mean_change_exp = 8.4, mean_change_sd_exp = 9.13,
  mean_change_nexp = 2.43, mean_change_sd_nexp = 6.61,
  r_pre_post_exp = 0.2, r_pre_post_nexp = 0.2
)

References

Bonett, S. B. (2008). Estimating effect sizes from pretest-posttest-control group designs. Organizational Research Methods, 11(2), 364–386. https://doi.org/10.1177/1094428106291059

Cooper, H., Hedges, L.V., & Valentine, J.C. (Eds.). (2019). The handbook of research synthesis and meta-analysis. Russell Sage Foundation.