# Estimating the IQ of Arthur Jensen

I once asked Jensen if he knew his own IQ. It turned out that he had never taken any of the standard tests, like the WAIS. The question of testing him first arose during the year of his Maryland internship, but by then he could not take the WAIS because he was too familiar with it (having administered it to others perhaps a hundred times). Of the various mental tests he has taken over the years, the Terman Concept Mastery Test (CMT) __ a high-level measure of verbal skills__probably provides the best approximation of an IQ test. Jensen took it when he was forty-three. He declined to tell me the score__and seemed distinctly unhappy at my interest in the subject__but did finally mention that his CMT score was about at the average of those members of Terman’s Gifted Group who had gone on to earn Ph.D.s.Poking my nose into volume 5 of Terman’s Genetic Studies of Genius, I learn that this subgroup of the gifted had Stanford-Binet IQ equivalents of 156, well into the 99.9 percentile. Which possibly helps to explain why Jensen has been such a dominant figure in the IQ debate.

-thanks to pumpkinperson - verified in page 63

Later on he claims that the true value is actually 159 - given my skepticism of these scores of above 155 I will conventionally round it to 155.

He also got a PhD from Columbia university. Currently 3% of Americans obtain a professional degree or PhD, and about 37% of them obtain college degrees according to my eduyears spreadsheet. At the time Jensen got his PhD, only 10% of men obtained college degrees. Taking the average of a very bullish estimate (3*10/36%) and bearish (3%) estimate of the number of American men with professional degrees puts Arthur Jensen’s eduttainment z-score at 2.13.

Currently assuming a correlation between verbal ability and IQ of 0.8 and a correlation of eduttainment with IQ of 0.55.

The simulation yielded an estimate of 145 with a standard error of 8.

```
g <- rnorm(60000000)
c <- 0.55*g + rnorm(60000000)*sqrt(1-0.55^2)
b <- 0.8*g + rnorm(60000000)*sqrt(1-0.8^2)
subby1 <- data.frame(g, c)
subby1$b <- b
subby2 <- subset(subby1, (subby1$b > 3.5 & subby1$b < 3.7) & (subby1$c > 2 & subby1$c < 2.25))
mean(subby2$g)
sd(subby2$g)
sd(g)
```