#http://DataColada.org/73 - R Code to calibrate effect of combining multiple p=.049, # Originally written for Vosgerau et al https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3271372 #Written by Uri Simonsohn (urisohn@gmail.com) #Please email directly if you see any errors or have any questions #Last update: 2018 10 24 ###################################################################################### #Function to compute variance of d vard=function(d,n) (2/n+(d^2)/(2*(2*n-2)))*((2*n)/(2*n-2)) #Cooper, Harris, Hedges, "Handbook of Research Synthesis 1993", p.238 #Library to run meta-analysis library(metafor) minimeta=function(p,n) { t=qt(1-p/2,2*n-2) #observed t-value d=2*t/sqrt(2*n-2) #observed effect size v=vard(d,n) #its variance p.f=rma(yi=d,vi=v,method='FE')$pval p.r=rma(yi=d,vi=v,method='REML')$pval cat("\nFixed effects",p.f) cat("\nRandom effects",p.r) } minimeta(p=c(.049,.20),n=c(50,50)) minimeta(p=c(.049,.20),n=c(80,80)) minimeta(p=c(.049,.20),n=c(1000,1000))