ss.aipe.cv: Sample size planning for the coefficient of variation given...

In MBESS: The MBESS R Package

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 be wider than desired. The value of C.of.V should be positive.

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 on 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; [e-mail])

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)

MBESS documentation built on Oct. 26, 2023, 9:07 a.m.