logical value determining, if a bias correction should be used (see. details). Default is FALSE.
conf.level
confidence level of the interval.
na.rm
logical. Should missing values be removed? Defaults to FALSE.
Value
if no confidence intervals are requested:
the estimate as numeric value (without any name)
else a named numeric vector with 3 elements
estestimate
lwr.cilower confidence interval
upr.ciupper confidence interval
Details
In order for the coefficient of variation to be an unbiased estimate of the true population value,
the coefficient of variation is corrected as: $$CV_{korr} = CV \cdot \left( 1 - \frac{1}{4\cdot(n-1)} + \frac{1}{n} \cdot CV^2 + \frac{1}{2 \cdot (n-1)^2} \right)$$
References
Johnson, B. L., Welch, B. L. (1940). Applications of the non-central t-distribution. Biometrika, 31, 362--389.
Kelley, K. (2007). Sample size planning for the coefcient of variation from the accuracy in parameter estimation approach. Behavior Research Methods, 39 (4), 755-766
Kelley, K. (2007). Constructing confidence intervals for standardized effect sizes: Theory, application, and implementation. Journal of Statistical Software, 20 (8), 1-24
McKay, A. T. (1932). Distribution of the coefficient of variation and the extended
t distribution, Journal of the Royal Statistical Society, 95, 695--698.
Smithson, M.J. (2003) Confidence Intervals, Quantitative Applications in the Social Sciences Series, No. 140. Thousand Oaks, CA: Sage. pp. 39-41