es_from_mean_change_pval {metaConvert}

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

Description

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

Usage

es_from_mean_change_pval(
  mean_change_exp,
  mean_change_pval_exp,
  mean_change_nexp,
  mean_change_pval_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_pval_exp

p-value 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_pval_nexp

p-value 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.

Details

This function converts the mean change and associated p-values of two independent groups into a Cohen's d. The Cohen's d is then converted to other effect size measures.

To start, this function estimates the mean change standard errors from the p-values:

t\_exp <- qt(p = mean\_change\_pval\_exp / 2, df = n\_exp - 1, lower.tail = FALSE)

t\_nexp <- qt(p = mean\_change\_pval\_nexp / 2, df = n\_nexp - 1, lower.tail = FALSE)

mean\_change\_se\_exp <- |\frac{mean\_change\_exp}{t\_exp}|

mean\_change\_se\_nexp <- |\frac{mean\_change\_nexp}{t\_nexp}|

Then, this function simply internally calls the es_from_means_se_pre_post function but setting:

mean\_pre\_exp = mean\_change\_exp

mean\_pre\_se\_exp = mean\_change\_se\_exp

mean\_exp = 0

mean\_se\_exp = 0

mean\_pre\_nexp = mean\_change\_nexp

mean\_pre\_se\_nexp = mean\_change\_se\_nexp

mean\_nexp = 0

mean\_se\_nexp = 0

To know more about other calculations, see es_from_means_sd_pre_post function.

Value

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/html/input.html

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.

Examples

es_from_mean_change_pval(
  n_exp = 36, n_nexp = 35,
  mean_change_exp = 8.4, mean_change_pval_exp = 0.13,
  mean_change_nexp = 2.43, mean_change_pval_nexp = 0.61,
  r_pre_post_exp = 0.8, r_pre_post_nexp = 0.8
)