transformZrtoHgapprox function

transformZrtoHgapprox

This function provides an approximate transformation from Zr to Hedges g when the number of observations in the treatment and control group are unknown. It is also used to allow the forest plots to display Hedge's g when they are based on r. It is necessary because the transformation function in the forest plot function does not allow any parameters other than effect size used. The function assumes that Nc=Nt and gives the same results as transformZrtoHg when Nc=Nt.

transformZrtoHgapprox(Zr)

Arguments

• Zr: A vector of normalised point bi-serial values

Returns

approx. value of Hedges' g

Examples

transformZrtoHgapprox(c(0.4, 0.2))
# [1] 0.8215047 0.4026720

Author(s)

Barbara Kitchenham and Lech Madeyski