PowerTOST (version 1.2-09)

CVCL: Confidence limits of a CV for log-normal data

Description

The function calculates the 1-alpha confidence limits (either 1-sided or 2-sided) via the chi-squared distribution of the error variance the CV is based on.

Usage

CVCL(CV, df, side = c("upper", "lower", "2-sided"), alpha = 0.05)

Arguments

CV

Coefficient of variation

df

degrees of freedom of the CV (error variance)

side

Side(s) to calculate the confidence limits for

alpha

Type I error probability, aka significance level

Value

• Numeric vector of the confidence limits named as 'lower CL' and 'upper CL'. In case of the one-sided upper confidence limit the 'lower CL' is = 0. In case of the one-sided lower confidence limit the 'upper CL' is = Inf.

Examples

# upper one-sided 95\% CL of a CV=0.3 
# from a study with df=22 (f.i. a 2x2 crossover with n=24)
# side="upper" is standard if not explicitly given
CVCL(0.3, df=22)
# should give:
# lower CL  upper CL 
#0.0000000 0.4075525