Estimating the IQ of John F Kennedy

Kennedy apparently scored a 124 on an IQ test when he was 14 (he didn’t score 119, as many believe - thank you pumpkinperson) - though I have reason to believe this is a rare case of regressing to the mean, but upwards. First of all, a male college graduate from this time period probably had an average IQ of about 118 - and JFK attended harvard as well, which probably had a higher IQ as well.

I’ll use his wealth as another source of information - he died with a net worth of 99 million. It’s true that he inherited it - though the correlation between wealth and IQ is agnostic to how it is inherited. It’s difficult to judge how many men that wealth there are - I’ll just use the same z-score I used for Joe Rogan (4).

Assuming reliability of IQ of 0.9 and a correlation between wealth and IQ of 0.2 results in an estimate of 124 with a standard error of 6.6 (so much for the regression upwards).

set.seed(1)
g <- rnorm(60000000, mean=0)
iq <- 0.9*g + rnorm(60000000)*sqrt(1-0.9^2)
sc <- 0.2*g + rnorm(60000000)*sqrt(1-0.2^2)

subby1 <- data.frame(iq, sc)
subby1$g = g
subby2 <- subset(subby1, (subby1$iq > 1.55 & subby1$iq < 1.65) & (subby1$sc > 3.8 & subby1$sc < 4.2))
mean(subby2$g)
sd(subby2$g)