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Bayes Factors and p-values for independent t-test
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p1 <-numeric(200) #set up empty container for all p-values | |
bf1 <-numeric(200) #set up empty container for all bf | |
p2 <-numeric(200) #set up empty container for all p-values | |
bf2 <-numeric(200) #set up empty container for all bf | |
p3 <-numeric(200) #set up empty container for all p-values | |
bf3 <-numeric(200) #set up empty container for all bf | |
t <- 1.96 #set start point t-value | |
for (i in 1:201) | |
{ | |
t<-t+0.01 | |
bf1[i]<-exp(-ttest.tstat(t,20,20,rscale=1)$bf) # calc BF | |
p1[i]<-2*pt(-abs(t),df=40-2) #calc p-value | |
bf2[i]<-exp(-ttest.tstat(t,50,50,rscale=1)$bf) | |
p2[i]<-2*pt(-abs(t),df=100-2) | |
bf3[i]<-exp(-ttest.tstat(t,100,100,rscale=1)$bf) | |
p3[i]<-2*pt(-abs(t),df=200-2) | |
} | |
#Below is a lot of syntax to draw the plot | |
plot(bf3,type='l', xaxt="n", xlab="t-values", ylab="Bayes Factor") | |
tvalues<-seq(1.96, 3.96, by=0.01) | |
axis(1, 1:201, side = 1, at = c(1, 50, 100, 150, 200), labels = c("1.96", "2.46", "2.96", "3.46", "3.96")) | |
legend(150,1.4, # places a legend at the appropriate place | |
c("N = 100","N = 50", "N = 20"), # puts text in the legend | |
lty=c(1,1), # gives the legend appropriate symbols (lines) | |
lwd=c(2.5,2.5,2.5),col=c("black", "red","blue")) # format lines and colors | |
#draw some horizontal and vertical lines | |
abline(h=0.1, col="azure3", lty=5) | |
abline(h=0.33, col="azure4", lty=5) | |
abline(v=7, col="blue", lty=3) | |
abline(v=3, col="red", lty=3) | |
abline(v=2, lty=3) | |
lines(bf2, col='red') | |
lines(bf1, ,col='blue') | |
#Draw p-value plot | |
plot(p3,type='l', xaxt="n", xlab="t-values", ylab="p-values") | |
tvalues<-seq(1.96, 3.96, by=0.01) | |
axis(1, 1:201, side = 1, at = c(1, 50, 100, 150, 200), labels = c("1.96", "2.46", "2.96", "3.46", "3.96")) | |
legend(150,0.045, # places a legend at the appropriate place | |
c("N = 100","N = 50", "N = 20"), # puts text in the legend | |
lty=c(1,1), # gives the legend appropriate symbols (lines) | |
lwd=c(2.5,2.5,2.5),col=c("black", "red","blue")) # format lines and colors | |
lines(p2, col='red') | |
lines(p1, col='blue') | |
abline(h=0.05, col="azure4", lty=5) | |
abline(h=0.01, col="azure3", lty=5) |
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