# R/ES.proportions.R In powerAnalysis: Power Analysis in Experimental Design

#### Documented in ES.proportions

```#' Compute effect size for a difference in proportions
#'
#' @param p1          Proportion of sample one
#' @param p2          Proportion of sample two or a constant proportion
#' @param alternative The test is two sided or one sided
#' @export
#' @examples
#' ES.proportions(0.65,0.45)
#'
#' ES.proportions(0.25,0.05)
ES.proportions <- function(p1=NULL, p2=NULL,alternative = c("two.sided", "one.sided")){
alternative <- match.arg(alternative)
if(is.null(p1) || is.null(p2)){
stop("'p1' and 'p2' can not be NULL")
}
if(p1 < 0 || p2 < 0 || p1>1 || p2>1){
stop("'p0' and 'p1' must be in [0,1]")
}
h=2*(asin(sqrt(p1))-asin(sqrt(p2)))

NOTE0="The alternative hypothesis is p1 > p2"
if(alternative =="two.sided"){
h <-abs(h)
NOTE0="The alternative hypothesis is p1 != p2"
}
NOTE1="small effect size:  h = 0.2"
NOTE2="medium effect size: h = 0.5"
NOTE3="large effect size:  h = 0.8"
NOTE=paste(NOTE0,NOTE1,NOTE2,NOTE3,sep="\n")
METHOD="effect size of the difference in proportions"
structure(list(h = h, p1 = p1, p2 = p2,note=NOTE,method=METHOD), class = "power.htest")
}
```

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powerAnalysis documentation built on May 2, 2019, 12:40 p.m.