ci.cronbach {statpsych} | R Documentation |
Confidence interval for a Cronbach reliability
Description
Computes a confidence interval for a population Cronbach reliability. The point estimate of Cronbach reliability assumes essentially tau-equivalent measurements and the confidence interval assumes parallel measurements.
Usage
ci.cronbach(alpha, rel, r, n)
Arguments
alpha |
alpha level for 1-alpha confidence |
rel |
estimated Cronbach reliability |
r |
number of measurements (items, raters, etc.) |
n |
sample size |
Value
Returns a 1-row matrix. The columns are:
Estimate - estimated Cronbach reliability (from input)
LL - lower limit of the confidence interval
UL - upper limit of the confidence interval
References
Feldt LS (1965). “The approximate sampling distribution of Kuder-Richardson reliability coefficient twenty.” Psychometrika, 30(3), 357–370. ISSN 0033-3123, doi:10.1007/BF02289499.
Examples
ci.cronbach(.05, .85, 7, 89)
# Should return:
# Estimate SE LL UL
# 0.85 0.02456518 0.7971254 0.8931436
[Package statpsych version 1.6.0 Index]