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ConfidenceIntervals-Noncentral.R
README.md

README.md

Confidence Intervals for Noncentrality Parameters

This script contains two functions to calculate the bounds of a confidence interval for the non-centrality parameter of the noncentral F- and t-Distribution. The bounds can be used to construct a confidence interval for effect size measures, an approach detailed by Steiger & Foulandi (1997) in Harlow et al. (1997) and used for ANOVA designs in Steiger (2004).

Example

> source('ConfidenceIntervals-Noncentral.R')
> confint.ncp.f(13.18, 1, 314)
$lower
[1] 2.713216

$upper
[1] 31.44969

> confint.ncp.t(3.04, 314, alpha=.99)
$lower
[1] 0.4429486

$upper
[1] 5.632345

Dependencies

None.

References

  • Harlow, L. L., Mulaik, S. A., & Steiger, J. H. (Eds.). (1997). What If There Were No Significance Tests? Mahwah, NJ: Lawrence Erlbaum Associates, Inc.
  • Steiger, J. H. (2004). Beyond the F Test: Effect Size Confidence Intervals and Tests of Close Fit in the Analysis of Variance and Contrast Analysis. Psychological Methods, 9(2), 164–182. http://doi.org/10.1037/1082-989X.9.2.164