Sample size for a 2-group Cronbach reliability difference confidence interval

Source: R/statpsych2.R

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

size.ci.cronbach2(alpha, rel1, rel2, r, w)

Arguments

alpha

alpha level for hypothesis test

rel1

group 1 reliability planning value

rel2

group 2 reliability planning value

r

number of measurements (items, raters)

w

desired confidence interval width

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.ci.cronbach2(.05, .85, .70, 8, .15)
#>  Sample size per group
#>                    180

# Should return:
# Sample size per group
#                   180