TIVA.R

# TIVA = Test of insufficient variance - see https://replicationindex.wordpress.com/2014/12/30/the-test-of-insufficient-variance-tiva-a-new-tool-for-the-detection-of-questionable-research-practices/
# code adapted from Moritz Heene

# This function assumes *one-tailed* p-values that all are directionally consistent!
TIVA <- function (p.values, log.p=FALSE) {
	if (log.p==FALSE) {
		p.values <- clamp(p.values, MIN=.000000001, MAX=1-.000000001)	# prevent infinite z-values
		z.values  <- qnorm(p.values, lower.tail = FALSE)
	} else {
		z.values  <- qnorm(p.values, lower.tail = FALSE, log.p=TRUE)
	}
	var.z  <- var(z.values)
	df <- length(p.values)-1
	chi.square  <- df*var.z
	chi.p  <- pchisq(chi.square, df=df, lower.tail = TRUE)
	data.frame(var.z=var.z, chi2=chi.square, df=df, p.value=chi.p)
}