ss.aipe.cv {MBESS}R Documentation

Sample size planning for the coefficient of variation given the goal of Accuracy in Parameter Estimation approach to sample size planning.

Description

Determines the necessary sample size so that the expected confidence interval width for the coefficient of variation will be sufficiently narrow, optionally with a desired degree of certainty that the interval will not wider than desired.

Usage

ss.aipe.cv(C.of.V = NULL, width = NULL, conf.level = 0.95, 
degree.of.certainty = NULL, assurance=NULL, certainty=NULL, 
mu = NULL, sigma = NULL, alpha.lower = NULL, alpha.upper = NULL, 
Suppress.Statement = TRUE, sup.int.warns = TRUE, ...)

Arguments

C.of.V population coefficient of variation which the sample size procedure is based
width desired (full) width of the confidence interval
conf.level confidence interval coverage; 1-Type I error rate
degree.of.certainty value with which confidence can be placed that describes the likelihood of obtaining a confidence interval less than the value specified (e.g., .80, .90, .95)
assurance an alias for degree.of.certainty
certainty an alias for degree.of.certainty
mu population mean (specified with sigma when C.of.V is not specified)
sigma population standard deviation (specified with mu when C.of.V) is not specified)
alpha.lower Type I error for the lower confidence limit
alpha.upper Type I error for the upper confidence limit
Suppress.Statement Suppress a message restating the input specifications
sup.int.warns suppress internal function warnings (e.g., warnings associated with qt)
... for modifying parameters of functions this function calls

Value

Returns the necessary sample size given the input specifications.

Author(s)

Ken Kelley (University of Notre Dame; KKelley@ND.Edu)

See Also

ss.aipe.cv.sensitivity, cv

Examples

# Suppose one wishes to have a confidence interval with an expected width of .10 
# for a 99% confidence interval when the population coefficient of variation is .25.
ss.aipe.cv(C.of.V=.1, width=.1, conf.level=.99)

# Ensuring that the confidence interval will be sufficiently narrow with a 99% 
# certainty for the situation above.
ss.aipe.cv(C.of.V=.1, width=.1, conf.level=.99, degree.of.certainty=.99)

[Package MBESS version 2.0.0 Index]