R/non_centrality_search_function.R

In genpwr: Power Calculations Under Genetic Model Misspecification

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#Search for Non-Centrality Parameter for SS calcualtion for 2Df Test
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#' Function to Determine Non-Centrality Parameter of the Chi-squared distribution
#'
#' This function is set to 0 and solved for x, the non-centrality parameter to determine the sample size in \code{\link{ss.calc}}
#'
#' @param x the non-centrality parameter
#' @param power the desired power
#' @param Alpha the desired type 1 error rate
#' @param df the degrees of freedom for the likelihood ratio test
#'
#' @return numeric value of the function
#'
#' @examples
#' ncp.search(x = 7.848861, pow = 0.8, Alpha = 0.05, df=1)
#'
#' @export
#'
ncp.search<- function(x, power, Alpha, df)
{
	(1 - power) - pchisq(qchisq(1 - Alpha, df, ncp=0), df=df, ncp = x)
}