se.stdmean2 {vcmeta}

Computes the standard error for a 2-group standardized mean difference

Description

This function computes the standard error of a 2-group standardized mean difference using the sample sizes and the estimated means standardizer (stdzr = 0) for 2-group experimental designs. Use the square root weighted variance standardizer (stdzr = 3) for 2-group nonexperimental designs with simple random sampling. The single-group standardizers (stdzr = 1 and stdzr = 2) can be used with either 2-group experimental or nonexperimental designs. The effect size estimate and standard error output from this function can be used as input in the meta.ave.gen, meta.lc.gen, and meta.lm.gen functions in applications where compatible standardized mean differences from a combination of 2-group and paired-samples experiments are used in the meta-analysis. Equality of variances is not assumed.

Usage

se.stdmean2(m1, m2, sd1, sd2, n1, n2, stdzr)

Arguments

m1

estimated mean for group 1

m2

estimated mean for group 2

sd1

estimated standard deviation for group 1

sd2

estimated standard deviation for group 2

n1

sample size for group 1

n2

sample size for group 2

stdzr

• set to 0 for square root average variance standardizer

• set to 1 for group 1 SD standardizer

• set to 2 for group 2 SD standardizer

• set to 3 for square root weighted variance standardizer

Value

Returns a one-row matrix:

• Estimate - estimated standardized mean difference

• SE - standard error

References

Bonett DG (2009). “Meta-analytic interval estimation for standardized and unstandardized mean differences.” Psychological Methods, 14(3), 225–238. ISSN 1939-1463, doi:10.1037/a0016619.

See Also

se.cohen

Examples

se.stdmean2(21.9, 16.1, 3.82, 3.21, 40, 40, 0)

# Should return: 
#                                Estimate        SE
# Standardized mean difference:  1.643894 0.2629049