Standardize Means Difference

Provides the standardized effect size for the difference and its confidence interval.

Usage

# S3 method for data.frame
standardizeMeansDifference(frame, mu=0, conf.level=.95, ...)

# S3 method for formula
standardizeMeansDifference(formula, mu=0, conf.level=.95, ...)

# S3 method for wsm
standardizeMeansDifference(moments, corrs, mu=0, conf.level=.95, ...)

# S3 method for bsm
standardizeMeansDifference(moments, mu=0, conf.level=.95, ...)

Arguments

frame

a set of (non-empty) numeric vectors of data values

formula

a formula of the form lhs ~ rhs where lhs is a numeric variable giving the data values and rhs a factor giving the corresponding groups

moments

a matrix/frame of descriptive/summary statistics

corrs

a matrix/frame of correlations among the measures

mu

a number indicating the true/hypothesized value of the mean difference

conf.level

confidence level of the interval

Details

This function compares two groups or variables. As such, the supplied factor or table of summary statistics should contain only two groups or two variables.

Value

The returned frame contains the following components:

d

the standardized mean difference

SE

the standard error of the standardized mean difference

LL

the lower limit of the confidence interval of the standardized mean difference

UL

the upper limit of the confidence interval of the standardized mean difference

References

Bonett, D. G. (2008). Confidence intervals for standardized linear contrasts of means. Psychological Methods, 13(2), 99-109.