sample.size.proportion.test.twosample.approximate <- function(proportion.g1
,proportion.g2
,alpha = .05
,beta = .1
,alternative = c("two.sided","less","greater")
,details = TRUE
,power.from.actual = F #report parameter power instead of true power
) {
validate.htest.alternative(alternative = alternative)
z_alpha <- qnorm(ifelse(alternative[1] == "two.sided",alpha/2,alpha), lower.tail = F)
z_beta <- qnorm(beta, lower.tail = F)
se.g1 <- proportion.g1*(1-proportion.g1)
se.g2 <- proportion.g2*(1-proportion.g2)
n <- ((z_alpha*sqrt(2*se.g1) + z_beta*sqrt(se.g1 + se.g2)) / (proportion.g1 - proportion.g2))^2
n.rounded <- ceiling(n)
if (power.from.actual) {
power <- 1-beta
} else {
#beta <- pnorm(sqrt(n.rounded) * effect.size/se.est - qnorm(ifelse(alternative[1] == "two.sided",alpha/2,alpha), lower.tail = F)
# , lower.tail = F)
power <- power.proportion.test.twosample.approximate(sample.size = n.rounded,
proportion.g1 = proportion.g1,
proportion.g2 = proportion.g2,
alpha=alpha,
alternative = alternative,
details=FALSE
)
beta <- 1-power
}
if (details) {
as.data.frame(list(test="proportion"
,type = "two.sample"
,alternative = alternative[1]
,sample.size = n.rounded
,actual = n
,proportion.g1 = proportion.g1
,proportion.g2 = proportion.g2
,alpha = alpha
,conf.level = 1-alpha
,beta = beta
,power = power
))
}
else {
n.rounded
}
}
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