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Confidence interval for a Cronbach reliability

Source: R/statpsych2.R
ci.cronbach.Rd

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.

For more details, see Section 4.19 of Bonett (2021, Volume 1)

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, forms)

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 .

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

Examples

ci.cronbach(.05, .85, 7, 89)
#>  Estimate      SE     LL     UL
#>      0.85 0.02457 0.7971 0.8932

# Should return:
# Estimate       SE     LL     UL
#     0.85  0.02457 0.7971 0.8932