Forked from sdchasalow/CI-binomial-simulation.R
Last active
June 2, 2016 18:59
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
# Fork of Scott's coin flip simulation | |
# https://gist.github.com/maptracker/e34a8596a9c2a7f261d6b892e5df42c5 | |
flipCoin <- function( n = 50, pvals = 0.5, nosim = 100, file = NULL ) { | |
coverage <- lapply(pvals, function(p) { | |
phats <- (rbinom(nosim, prob = p, size = n) + 2)/(n + 4) | |
ll <- phats - qnorm(0.975) * sqrt(phats * (1 - phats)/n) | |
ul <- phats + qnorm(0.975) * sqrt(phats * (1 - phats)/n) | |
cbind(lower = ll, upper = ul) | |
})[[1]] # De-listify | |
if (!is.null(file)) png(file) | |
plot(0:1, c(0, nosim + 1), type = 'n', | |
xlab = "95% CI for p", ylab = "Replicate Number") | |
abline(v = pvals, lty = 2, col = "blue") | |
## Highlight ranges that do not cover the true mean | |
color <- apply(coverage, 1, function (x) { | |
ifelse(x[1] <= pvals && pvals <= x[2], "black", "red") | |
}) | |
segments(coverage[,1], 1:nosim, coverage[, 2], 1:nosim, col = color) | |
## Draw a density plot (bar) of overlapping coverages | |
alpha <- as.integer(255 / nosim) | |
if (alpha < 1) alpha <- 1 | |
rect(coverage[,1], 0, coverage[, 2], nosim/-20, | |
col = rgb(0,0,0,alpha, maxColorValue = 255), border = NA) | |
title(sprintf("Simulating %s coin flips, %d replicates\nTrue p = %s", | |
n, nosim, pvals)) | |
if (!is.null(file)) dev.off() | |
coverage | |
} | |
c <- flipCoin() | |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Please give me a pull request. Thanks for the corrections and enhancements.