PowerTOST (version 1.4-6)

CI.RatioF: 1-2*alpha Fieller confidence interval given point est., CV (,CVb) and n

Description

Utility function to calculate the 1-2*alpha Fieller CI's given point est., CV (, CVb) and n for the parallel group and 2x2 crossover.

Usage

CI.RatioF(alpha = 0.025, pe, CV, CVb, n, design = c("2x2", "parallel"))

Arguments

alpha

Type I error probability, aka significance level. Defaults here to 0.025 because this function is intended for studies with clinical endpoints.

pe

point estimate of ratio T/R.

CV

Coefficient of variation as ratio. In case of design="parallel" this is the CV of the total variability, in case of design="2x2" the intra-subject CV.

CVb

CV of the between-subject variability. Only necessary for design="2x2".

n

Total number of subjects if a scalar is given. Number of subjects in (sequence) groups if given as vector.

design

A character string describing the study design. design="parallel" or design="2x2" allowed for a two-parallel group design or a classical TR/RT crossover design.

Value

Returns the 1-2*alpha confidence interval.

Details

The CV(within) and CVb(etween) in case of design="2x2" are obtained via an appropriate ANOVA from the error term and from the difference (MS(subject within sequence)-MS(error))/2.

References

Locke C.S. "An exact confidence interval from untransformed data for the ratio of two formulation means." J Pharmacokinet Biopharm. 12(6):649-55 (1984)

Hauschke D., Steinijans V. and Pigeot I. "Bioequivalence Studies in Drug Development" Chapter 10., John Wiley & Sons, Chichester (2007)

See Also

CI.BE, power.RatioF

Examples

# NOT RUN {
# 95% Fieller CI for the 2x2 crossover
CI.RatioF(pe=1.05,CV=0.3,CVb=0.6, n=24)
# }