R: sample size necessary for the accuracy in parameter...

ss.aipe.reg.coef {MBESS}

R Documentation

sample size necessary for the accuracy in parameter estimation approach for a regression coefficient of interest

Description

A function used to plan sample size from the accuracy in parameter estimation approach for a regression coefficient of interest given the input specification.

Usage

ss.aipe.reg.coef(Rho2.Y_X=NULL, Rho2.j_X.without.j=NULL, p=NULL, 
b.j=NULL, width, which.width="Full", sigma.Y=1, sigma.X=1, RHO.XX=NULL, 
Rho.YX=NULL, which.predictor=NULL, Noncentral=FALSE, alpha.lower=NULL,
alpha.upper=NULL, conf.level=.95, degree.of.certainty=NULL, assurance=NULL, 
certainty=NULL, Suppress.Statement=FALSE)

Arguments

`Rho2.Y_X`	Population value of the squared multiple correlation coefficient
`Rho2.j_X.without.j`	Population value of the squared multiple correlation coefficient predicting the `j`th predictor variable from the remaining `p`-1 predictor variables
`p`	the number of predictor variables
`b.j`	the regression coefficient for the `j`th predictor variable (i.e., the predictor of interest)
`width`	the desired width of the confidence interval
`which.width`	which width (`"Full"`, `"Lower"`, or `"Upper"`) the width refers to (at present, only `"Full"` can be specified)
`sigma.Y`	the population standard deviation of `Y` (i.e., the dependent variables)
`sigma.X`	the population standard deviation of the `j`th `X` variable (i.e., the predictor variable of interest)
`RHO.XX`	Population correlation matrix for the `p` predictor variables
`Rho.YX`	Population `p` length vector of correlation between the dependent variable (`Y`) and the `p` independent variables
`which.predictor`	identifies which of the `p` predictors is of interest
`Noncentral`	specify with a `TRUE`/`FALSE` statement whether or not the noncentral approach to sample size planning should be used
`alpha.lower`	Type I error rate for the lower confidence interval limit
`alpha.upper`	Type I error rate for the upper confidence interval limit
`conf.level`	desired level of confidence for the computed interval (i.e., 1 - the Type I error rate)
`degree.of.certainty`	degree of certainty that the obtained confidence interval will be sufficiently narrow
`assurance`	an alias for `degree.of.certainty`
`certainty`	an alias for `degree.of.certainty`
`Suppress.Statement`	`TRUE`/`FALSE` statement whether or not a sentence describing the situation defined is printed with the necessary sample size

Details

Not all of the arguments need to be specified, only those that provide all of the necessary information so that the sample size can be determined for the conditions specified.

Value

Returns the necessary sample size in order for the goals of accuracy in parameter estimation to be satisfied for the confidence interval for a particular regression coefficient given the input specifications.

Author(s)

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

References

Kelley, K. \& Maxwel, S. E. (2003). Sample size for Multiple Regression: Obtaining regression coefficients that are accuracy, not simply significant. Psychological Methods, 8, 305–321.

Examples

# Exchangable correlation structure
# Rho.YX <- c(.3, .3, .3, .3, .3)
# RHO.XX <- rbind(c(1, .5, .5, .5, .5), c(.5, 1, .5, .5, .5), c(.5, .5, 1, .5, .5), 
# c(.5, .5, .5, 1, .5), c(.5, .5, .5, .5, 1))
# ss.aipe.reg.coef(width=.1, which.width="Full", sigma.Y=1, sigma.X=1, RHO.XX=RHO.XX,
# Rho.YX=Rho.YX, which.predictor=1, Noncentral=FALSE, conf.level=1-.05, 
# degree.of.certainty=NULL, Suppress.Statement=FALSE)

# ss.aipe.reg.coef(width=.1, which.width="Full", sigma.Y=1, sigma.X=1, RHO.XX=RHO.XX,
# Rho.YX=Rho.YX, which.predictor=1, Noncentral=FALSE, conf.level=1-.05, 
# degree.of.certainty=.85, Suppress.Statement=FALSE)

# ss.aipe.reg.coef(width=.1, which.width="Full", sigma.Y=1, sigma.X=1, RHO.XX=RHO.XX,
# Rho.YX=Rho.YX, which.predictor=1, Noncentral=TRUE, conf.level=1-.05,
# degree.of.certainty=NULL, Suppress.Statement=FALSE)

# ss.aipe.reg.coef(width=.1, which.width="Full", sigma.Y=1, sigma.X=1, RHO.XX=RHO.XX, 
# Rho.YX=Rho.YX, which.predictor=1, Noncentral=TRUE, conf.level=1-.05, 
# degree.of.certainty=.85, Suppress.Statement=FALSE)

[Package MBESS version 3.3.3 Index]