Sample size to test equality of Cronbach reliability coefficients in a 2-group design

Computes the sample size required to test a difference in population Cronbach reliability coefficients with desired power in a 2-group design.

Usage

size.test.cronbach2(alpha, pow, rel1, rel2, r)

Arguments

alpha: alpha level for hypothesis test
pow: desired power
rel1: reliability planning value for group 1
rel2: reliability planning value for group 2
r: number of measurements (items, raters, forms)

Value

Returns the required sample size for each group

References

Bonett DG, Wright TA (2015). “Cronbach's alpha reliability: Interval estimation, hypothesis testing, and sample size planning.” Journal of Organizational Behavior, 36(1), 3–15. ISSN 08943796, doi:10.1002/job.1960 .

Examples

size.test.cronbach2(.05, .80, .85, .70, 8)
#>  Sample size per group
#>                     77

# Should return:
# Sample size per group
#                    77