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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

Details

For more details, see Section 2.19 of Bonett (2021, Volume 4)

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 .

Bonett DG (2021). Statistical Methods for Psychologists https://dgbonett.sites.ucsc.edu/.

Examples

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

# Should return:
# Sample size per group
#                   180