size.ci.cronbach2 {statpsych}

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

Description

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

Usage

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)

# Should return:
# Sample size per group
#                   180