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

Source: R/statpsych2.R
size.ci.cronbach2.Rd

Computes the sample size per group (assuming equal sample sizes) 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

reliability planning value for group 1

rel2

reliability planning value for group 2

r

number of measurements (items, raters, forms)

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