psychmeta (version 2.7.0)

var_error_g: Estimate the error variance Hedges's \(g\) values

Description

Allows for error variance to be estimated using total sample size of both groups being compared (in this case, supply sample sizes using only the n1 argument) or using separate sample sizes for group 1 and group 2 (i.e., the groups being compared; in this case, supply sample sizes using both the n1 and n2 arguments).

Usage

var_error_g(g, n1, n2 = NA, a_method = c("gamma", "approx"))

Value

A vector of sampling-error variances.

Arguments

g

Vector of Hedges's \(g\) values.

n1

Vector of sample sizes from group 1 (or the total sample size with the assumption that groups are of equal size, if no group 2 sample size is supplied).

n2

Vector of sample sizes from group 2.

a_method

Method used to correct the bias in Cohen's d to convert to Hedges's g. Options are "gamma" (default) for the exact method based on the gamma function (Hedges & Olkin, 1985) or "approx" for the computationally trivial approximation (Borenstein et al., 2006).

References

Hedges, L. V., & Olkin, I. (1985). Statistical methods for meta-analysis. Academic Press. p. 104

Borenstein, M., Hedges, L. V., Higgins, J. P. T., & Rothstein, H. R. (2009). Introduction to meta-analysis. Wiley. p. 27.

Examples

var_error_g(g = 1, n1 = 30, n2 = 30)
var_error_g(g = 1, n1 = 60, n2 = NA)