For type I error, alpha, dfgp-1 groups, with dfc covariates to detect a R-squared of size, rsq, wiuth power, pow requires a total sample size of n.
[COPY AND PASTE INTO R AND ADJUST AS DESIRED]
pow <- 0.9 alpha <- 0.05 dfgp <- 4 dfc <- 1 rsq <- 0.1
[COPY AND PASTE THE BELOW TO OUTPUT N]
n <- 2+dfgp+dfc
fn <- function(n) {
(pow - (1 - pf(abs(qf(1-alpha,dfgp,n-dfgp-dfc-1)),dfgp,
n-dfgp-dfc-1,ncp=n*rsq/(1-rsq))))
}
while (fn(n) > 0) n <- n + 1
print(n)