Adult Termites' IQ Distribution,
vs. a Gaussian IQ Distribution
Figure 1 below shows a plot of the distribution of the adult Termites' deviation IQs (standard deviation = 16), as measured by the CMT-A test, versus the Gaussian distribution of deviation IQs expected in the adult population of 160,000 of the children in the "main group" who were screened by Terman, et al, in 1921-22. I have truncated the Gaussian distribution so that it show no scores below deviation-IQ = 136 in order to avoid swamping the Termites' data.
Figure 2 presents the full set of data.
Figure 1 tells a shocking story. The IQs distribution depicted by the Gaussian (pink) curve is, by definition, the distribution that we would expect to find in a randomly-selected population of 160,000 adults above a deviation IQ of 135. (I haven't included the rest of the Gaussian (for IQs below 136) in Figure 1 because it would swamp the rest of the data, as you can see in Figure 2 below.)
About 820 of the adults in a randomly-selected population would have deviation IQs ranging between 136 and 140, compared with only 51 of the Termites. In other words, as adults in 1940, only about 1/16th of the adults with IQs between 136 and 140 were enrollees in Dr. Terman's Study.
About 434 adults would have been expected with adult deviation IQs between 140 and 144, of whom 64 would have been Termites. In other words, about 6 out of every 7 adults drawn from the original population of 160,000 schoolchildren in Dr. Terman's "main group" who had Adult IQs between 140 and 144 wouldn't have been included in Dr. Terman's Study.
About 196 adults with deviation IQs between 144 and 148 should be found, of whom 60, or about 3 out of 10 would have been Termites.
About 110 adults with deviation IQs between 148 and 152 would be expected, and about 46 of them would be Termites.
About 36 adults with IQs between 152 and 156 would be expected, whereas there are 52 Termites with those scores. As both Figure 1 and Table 1 reveal, there is excellent agreement between the Gaussian curve and the Termites' curve above an IQ of 152. This is consistent with the idea that the Terman screening recruited all of the very brightest kids.
To sum it up, practically all the adults with IQs above 152 were Termites. Fewer than half of the adults with IQs below 152 were Termites dropping to one gifted adult out of every 16 with IQs below 140. In other words, the majority of all the gifted adults with IQs below 152 were overlooked by the Terman study.
To reiterate, the pink curve represents all the individuals who were screened for possible inclusion in the Terman study, while the blue curve shows the individuals who actually were selected for the study. The pink curve is the upper end (IQ = 136+) of the actual distribution of deviation IQs of the 160,000 adults whom Terman screened, as children, for his study back in 1921.
Figure 1 - The (Gaussian) distribution of deviation IQs among 160,000 adults versus the distribution of adult IQs among the Termites.
Figure 2, below, shows the full range of expected IQs for the upper half of 160,000 adults versus the Termites' adult IQs, as measured on the CMT-A in 1940. Table 1 shows the data in Figure 2.
Table 1. - The Distributions of Termite IQs versus the Distribution of IQs in the Entire Population
I derive two conclusions from this.
First, it's no wonder the Termites' didn't include any geniuses. The very smartest members of the candidate population may have been Termites, but a large fraction of the not-as-smart but still exceedingly intelligent adults were excluded from the Termites' group.
Second, there has been quite a bit of "percolation" of IQs, with nearly half the adult Termites falling below the 140 Stanford-Binet/136 deviation-IQ threshold for the Terman Study. Perhaps, a fifth of the Termites fell far enough below the threshold that mere test-retest regression doesn't explain it.
Quantitatively, there were 22 children in the Terman "main group" with childhood deviation IQs between 128 and 136. There were 160 children with IQs between 136 and 140.
Looking at the table above, there are 22 adults with deviation IQs ranging between 104 and 116, 35 adults with IQs below 120, 70 adults with IQs below 124, 100 adults with IQs below 128, and 49 adults with IQs between 128 and 132. About five points of test-retest decline would be expected on retaking the same test, and about eight points of decline would be predicted upon taking a different test.
If we were to reduce the childhood deviation IQs by eight points, we would have 22 children in the main group with IQs between 120 and 128, and 160 children with IQs between 128 and 132. Comparing that with Table 1 above, all 35 of the adult males with IQs below 120 actually lost IQ points growing into adulthood. After subtracting 8 points for test-retest and cross-test IQ losses there were 22 children with IQs below 128, but 100 adults with IQs below 128. Obviously, there was serious decline here, too. Note that the Termites' places are taken by other adults .. 6,100 of them with IQs between 120 and 128, and 38,300 with IQs between 104 and 120.
Richard M. Nixon was a Termites, so at least one of them attained a high level of eminence.