Sample size for a Cronbach reliability confidence interval

Computes the sample size required to estimate a Cronbach reliability with desired confidence interval precision. Set the reliability planning value to the smallest value within a plausible range for a conservatively large sample size.

Usage

size.ci.cronbach(alpha, rel, r, w)

Arguments

alpha

alpha value for 1-alpha confidence

rel

reliability planning value

r

number of measurements (items, raters, forms)

w

desired confidence interval width

Value

Returns the required sample size

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.cronbach(.05, .85, 5, .1)
#>  Sample size
#>           89

# Should return:
# Sample size
#          89