var_dif_rmd: var_dif_rmd

In RobbievanAert/puniform: Meta-Analysis Methods Correcting for Publication Bias

var_dif_rmd

Description

Function for computing the variance of the difference between two raw mean differences.

Usage

var_dif_rmd(sd1i, sd2i, n1i, n2i, r)

Arguments

sd1i	A vector of standard deviations of the outcomes in group 1 (see Details)
sd2i	A vector of standard deviations of the outcomes in group 2 (see Details)
n1i	An integer specifying the sample size of group 1
n2i	An integer specifying the sample size of group 2
r	A numerical value specifying the Pearson correlation coefficient between participants' scores on the different outcomes

Details

Multiple raw mean differences can be computed in case of two groups and multiple outcomes. The function computes the variance of the difference of two raw mean differences given a correlation between the outcomes. For a derivation of this variance see the supplemental materials of van Aert & Wicherts (2023).

The vectors sd1i and sd2i can contain a single standard deviation or multiple standard deviations if information on more than one outcome measure is available.

The variance that is computed with this function can be used to correct for outcome reporting bias by including the variance as a moderator in a (multivariate) meta-analysis. Please see van Aert & Wicherts (2023) for more information.

Value

The var_dif_rmd function returns a numerical value that is the variance of the difference of two raw mean differences given r.

Author(s)

Robbie C.M. van Aert [e-mail]

References

van Aert, R.C.M. & Wicherts, J.M. (2023). Correcting for outcome reporting bias in a meta-analysis: A meta-regression approach. Behavior Research Methods.

Examples

### Compute variance for an artificial example
var_dif_rmd(sd1i = c(0.8, 1.2), sd2i = c(0.85, 1.15), n1i = 100, n2i = 95, r = 0.3)

RobbievanAert/puniform documentation built on Sept. 22, 2023, 2:53 a.m.