MBESS: ss.aipe.cv – R documentation

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ss.aipe.cv

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; KKelley@ND.Edu)

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

The MBESS R Package

v4.8.0

GPL-2 | GPL-3

Authors

Ken Kelley [aut, cre]

Initial release

2020-08-04