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

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

Arguments

alpha

alpha level for hypothesis test

pow

desired power

rel1

group 1 reliability planning value

rel2

group 2 reliability planning value

r

number of measurements (items, raters)

Value

Returns the required sample size per 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
#> [1,]                    77

# Should return:
#      Sample size per group
# [1,]                    77