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Measuring Adult IQs: the Terman Concept Mastery Tests (CMTA and CMTB)
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Measuring
the "Termites" Adult IQs in 1940: The Concept Mastery IQ TestA (CMTA)
In 1940, when the "termites" were in their latter
twenties to early thirties, Dr.
Terman and his associates faced the task of measuring the Termites' adult
IQs.
Terman, et al, decided to develop a new IQ test for this purpose called the Concept Mastery Test
(CMT).
This is a 190question, highrange test, that was sufficiently difficult that
the highest raw score made by any Termite was 172. The average score of the Termites
on this test was 96, with the men averaging 98 and the women averaging
94. Nine
hundred fiftyfour (954) of the original 1,528 Termites took the CMT in
1940. Dr.
Quinn McNemar, who contributed to the statistical analysis of the data,
estimated that the average raw score of the average adult on the CMT (later
dubbed the CMTA) would be 2,
and that the Termites ranked about 2.1 standard deviations above the mean. Dr.
Terman insinuated that a standard deviation of 2.5 was more in line with the
Termite's average of 96, and this is what later researchers seem to have
accepted. This conclusion that the Termites' average score of 96
is 2.5 standard deviations above the average
(= 2) for the general population implies a
standard deviation on this test of 94/2.5 of 37.6
above the population mean of 2.
If zscores on this test are directly proportional to raw
scores, then this would imply the conversion table of raw scores to deviation
IQs shown in Table 1 below. What I'm saying
here is that there's no a priori reason why IQs should be directly proportional
to raw scores on an IQ test. However, for some reason, that seems to be the case
with the CMT tests. Perhaps they were designed that way.
Table 1 
Table
Converting CMTA Raw Scores to IQs, Assuming an Average Adult IQ Score for the
Termites That Is 2.5 Standard Deviations Above the Mean of the General
Population
CMT Score  2  10  20  30  40  50  60  70  80  90  96  110  120  130  140  150  160  172 
IQ Range 
100  103  108  112  116  120  125  129  133  137  140  146  150  154  159  163  167  172 
This is a very reasonable set of numbers.
Another,
Independent Approach:
Since we know
the expected deviationIQ distribution among the 260,000 people from whom the
Termites were drawn, we can use this information to norm IQ tests that the
Termites take, such as the CMTA.
We can draw
upon the fact that, out of 260,000 people, one would expect to find one person
with a 1in260,000 IQ (171+), two with 2 with 1in 130,000 IQs (169+), three
with 1in90,000 IQs (168+), and so forth. (Of course, there would be a 1in2
chance of finding someone with a 1in520,000 IQ of 174+ in our sample, and a
1in4 chance of finding someone with a 1in1,040,000 IQ of 176+ in our sample.)
A completely independent way to arrive at this
set of numbers is to assume that the two highest scorers had IQs at the 1 in
160,000andup level. That would correspond to a deviation IQ of 170, and would
imply a standard deviation of 38.4 points of raw score.
But in order to apply
this method to the Termites, I've had to make three perhapsquestionable
assumptions:
(1) I'm assuming that the population from which the
Termites were drawn is a randomly selected population.
This assumption may not
be entirely justified. Because Dr. Terman sifted the urban populations of San Francisco, Alameda,
Berkeley, Oakland, and Los Angeles, and because 35% of his enrollees came from
professional families, the chances of finding somewhat higher than expected IQs
might have been greater than it would have been had the children been enlisted
from, e. g., rural Iowa.
(2) I'm assuming that virtually all the brightest
children among the population of 260,000 children were included as Termites in
the Terman Study.
I'm betting that the testers missed some children at the lower
IQ levels, but that they identified and recruited those at the highest IQ
levels.
(3) I'm assuming that virtually all of the brightest
among the 260,000 adults were Termites, and took the CMTA in 1940.
However, even if these
assumptions aren't strictly valid, the results aren't very sensitive to the
assumptions.
Even if some of these assumptions aren't completely valid,
the results are relatively insensitive to deviations. For example, if these
scores are off by a factor of 2, the effect upon the range of IQs would only
be to shift the scale by about 2 points of IQ.
Table 2, below, shows the consequences of this independent
approach to norming the CMTA.
CMT Score  2  10  20  30  40  50  60  70  80  90  96  110  120  130  140  150  160  172 
IQ Range 
100  103  108  112  116  120  124  128  133  137  140  145  149  153  158  162  166  170 
Both of these tables agree
with the value of 2.5 standard deviations above the mean for the average CMT
score of 96 for the Termites who took the CMTA in 1940.
Table 1, above, yields a ceiling IQ for the CMTA of
180 (5 sigma above the mean for the general population).
Table 2 implies a ceiling of
178 (4.875 sigma
above the mean for the general population) on the test,
although these ceilings might be expected to be subject to ceiling effects starting at a raw score
of 171 (10% below the test's actual maximum raw score of
190).
In carrying out comparisons between the 192122
StanfordBinet IQs and the 1940 adult CMTA
IQs, I've had to limit myself to the
643 children in Dr. Terman's "main group", drawn from 160,000
schoolchildren, versus the 954 adults who took the
CMTA in 1940. The reason
I had to restrict my attention to the 643 children in the "main group"
is because that's the only group for whom adequate statistics are available to
me.
Male vs.
Female IQs During Childhood and Adulthood
The reason I considered only adult males is because, although
IQ tests are designed so that boys and girls have equally high IQs in childhood,
female IQ scores, on average, drop a few points during adolescence relative to
male IQ scores, apparently in response to hormonal changes. On the CMTA, the
women scored only about 2 points of IQ lower than the men, but on a test
emphasizing spatial and arithmetic abilities, the disparity would probably have been
greater.
One of the crucial questions this raises is: if women's IQs
are falling during adolescence, what does this do to the average IQ of the
population, and to the distribution of adult IQs? Does the average IQ of
schoolchildren drop a few points as they grow up?
Measuring
the "Termites" Adult IQs in 1952: The Concept Mastery IQ TestT (CMTT)
In 1951,
an updated version of the CMTA was
developed to measure the Termites' IQs at midlife (average
age: 41). Ten easier synonymantonyms and 5 easier analogies were
added to replace 15 of the most difficult synonymantonyms on the CMTA. The 15
most difficult synonymantonyms were eliminated because they were so seldom
answered that they had little discriminatory power when the CMTA was
administered in 1940. They were replaced by easy synonymantonyms and analogies
so that the test would have more room at the bottom so that it could be given to
less lofty scorers for normalization purposes. (The way I read the tea leaves,
this turned out to be a mistake. After correcting for differences in test
difficulty, the Termites scored, on average, about 16
points higher than they had in 1940,
and that extra ceiling was needed. But Terman and company presumably didn't know
that when they redesigned the test.)
Generallyspeaking, it looks as though the CMTT was,
perhaps, 15to20 points of raw score easier than the CMTA (for people the
same age (average age of 29.5) as the Termites were in 1940). This should
come as no surprise, since the 15 most difficult questions, that were rarely
answered, anyway, were removed from the CMTA, and were replaced with 15
quiteeasy questions.
It turns out that the ages of the takers is important on
these CMT tests.
Using the same kinds of norming that we used for the CMTA,
we would place the ceiling of the test (a raw
score of 190) at a deviation
IQ of, perhaps, 168, or 4.25
standard deviations above the general population mean.
CMTT Score  27  30  40  50  60  70  80  90  100  110  120  130  140  150  160  170  180  190 
IQ Range 
100  101  105  110  114  118  122  126  130  135  139  143  147  151  155  160  164  168 
Comparing
the CMTT with the CMTA
In order to try to find out how the two versions of the CMT
compared, both the CMTA and the CMTT were given in rapid succession to 108
undergraduate students at Stanford, to 40 graduate students at the University of
California, and to 341 Air Force captains tested by the University of
California. The interval between the administration of the two versions of the
CMT ranged from one day to one week.
The University of California
students averaged 21 points
higher on the CMTT
than they did on the CMTA (with a 95.6
average on the CMTT vs. a 74.6
average on the CMTA).
The Air Force captains
averaged 17.4 points
higher on the CMTT
than they did on the CMTA (with a 60.2
average on the CMTT vs. a 42.8
average on the CMTA).
But:
The Termites, taking the CMTT 12
years after they took the CMTA,
averaged about 40 points higher on the CMTT
than they made on the CMTA (with a 136.7
average on the CMTT vs. a 96.9
average on the CMTA). .
The Termites' spouses averaged about 33
points higher on the CMTT than
they did on the CMTA (with a 95.3
average on the CMTT vs. a 62.1
average on the CMTA).
Using a "line of equivalents", Dr. Terman, et al,
concluded that the Termites' raw scores (as measured by the concept Mastery
Tests) had risen by about 16 points between 1940 and
1952, corresponding to an increase in IQ
of about 16/38 X 16 = 6.75 points of IQ. In
other words, the IQs of the Termites had increased,
on average, almost 7 points
over a 12year interval.
This illuminates the distinction between fluid intelligence
and crystallized intelligence. On an absolute scale, fluid intelligence
decreases rapidly with increasing age, whereas crystallized intelligence can
rise with advancing age.
The bar chart below shows the raw scores earned by the adult
"Termites" in 1952 on the Concept Mastery TestT (CMTT). The average
of the adult "Termite" scores on this test was 136.7 (Genetic
Studies of Genius: Volume V, "The Gifted Group at MidLife",
ThirtyFive Years' FollowUp of the Superior Child, Lewis M. Terman and
Melissa H. Oden, Stanford University Press, Stanford, California, 1959, pgs.
5263 ).
As may be seen from the bar charts below, there were severe
ceiling effects for the CMTT test scores made by all the groups taking the
test.
, taken from the Prometheus Society's Membership
Committee Report,
Converting
the Termites' Childhood StanfordBinet Scores to Deviation IQs
Table 3, below, shows, in Column 2, the numbers of
individuals with a deviation IQ equal to or greater than the IQ in Column 1 whom
we would expect per 260,000 members of a randomly selected population. This
should give us the numbers of children at or above a given deviation IQ
For example, 1% of a randomly selected population has a deviation IQ of 137 or
above. Therefore, out of a population of 260,000, we would expect to find 2,600
with a deviation IQ of 137+. Similarly, since a deviation IQ of 150+ occurs
among 1 in 1,100 people, we would expect to find about 236 of the 260,000 with
deviation IQs of 150+. Similarly, since a deviation IQ of 160+ occurs about once
in every 11,000 people, we would expect to find about 24 such indivduals among
our 260,000.
Table 3 
LeftHand
Side: The 1st column shows deviation
IQs
RightHand Side The number expected at each IQ range among
260,000 people
Table 4, to the right of Table 3, shows numbers of children
arranged so that they match the predicted numbers in Table 3
. The purpose of this matchup is to try to relate the children's
StanfordBinet IQs with their expected deviation IQs by equating the frequencies
of occurrence of the various StanfordBinet IQs with the deviation IQs that
correspond to those frequencies of occurrence.
For example, during the initial Terman screening of 260,000
schoolchildren in 192122, 26 children, or about one child in 10,000, were found
with IQs of 180+. But a 1 in 10,000 frequency of occurrence corresponds to a
deviation IQ of about 159.5, so we might associate a StanfordBinet IQ of 180+
with a deviation IQ of 159.5+.
Similarly, 77 children were identified with StanfordBinet
IQs of 170+, or about 1 child in every 3,375. About 1 child in every 3,400 has a
deviation IQ of 155+, so we might associate a deviation IQ of 155+ with a
StanfordBinet IQ of 170+.
This matchup strategy has been used to associate the
deviation IQs shown in Column 1 of Table 3 with the childhood StanfordBinet IQs
of the children in Column 2 of Table 4
Table 4  LeftHand Side:
The
1st column shows the number of Termites observed (as children) with a given IQ
RightHand Side The 2nd column shows the StanfordBinet IQs
of these children
Table 3 Table 4
Dev. IQ  Predicted # 
Observed 
Observed 

171  1  1  200+  
169+  2  2  195+  
168+  3  3  192+  
167+  4  5  190+  
166+  5  188+  
165+  6  187+  
164+  9  9  185+  
163+  11  184+  
162+  14  183+  
161+  17  182+  
160+  24  26  180+  
159+  29  178+  
158+  37  35  175.5+  
157+  52  45  174.5+  
156+  65  172+  
155+  76  77  170  
154+  96  167.5+  
153+  118  114  165+  
152+  152  162.5+  
151+  186  183  160+  
150+  236  158+  
149+  288  288  155+  
148+  371  153  
147+  433  151.5  
146+  520  505  150+  
145+  650  147.5  
144+  765  749  145+  
143+  929  142.5  
142+  1,030  1,009  140+  
141+  1,360  
140+  1,625  
139+  1,860  
138+  2,360  
137+  2,600  
136+  3,250 
Table 3  Expected Frequencies of Occurrence Among 260,000 Randomly Selected People
(Table 3 is an abridged version of Table 1.)
Deviation IQ  140+  145+  150+  155+  160+  165+  171+ 
Expected #  1,625  650  236  76  24  6  1 
Table
4, below, shows in:
Column (1) the actual CMTA raw scores
of the male Termites,
Column (2) the number of scorers in the
10point interval, and
Column (3) the running total, starting from
the highest score (of 172) that any of them got, and proceeding down to the
lowest scoring range
Table 4
 Raw Scores on the CMTA
Scores 
# 
Cum. 
172  2  2 
160169  5  7 
150159  14  21 
140149  24  45 
130139  52  97 
120129  46  143 
110119  60  203 
100109  64  267 
9099  51  318 
8089  60  378 
7079  49  427 
6069  30  457 
5059  35  492 
4049  13  505 
3039  19  524 
2029  2  526 
1019  1  527 
09  0  527 
Now all we
have to do is match up the raw scores and cumulative numbers in Table 4 with the
equivalent IQs and predicted numbers in Table 1. When we do this, we get
Table 5
 Relating Raw Scores on the CMTA to the Expected (Gaussian) IQ Distribution
among 260,000 People
CMT Score  10  20  30  40  50  60  70  80  90  100  110  120  130  140  150  160  172 
IQ Range 
104  108  112  116  120  124  128  132  136  140  144  148  152  156  160  164  168 
Termites  1  2  19  13  35  30  49  60  51  64  60  46  52  24  14  5  2 
Gaussian  11,500  11,000  9,000  6,800  4,900  3,800  2,300  1,300  820  434  196  111  36  20  12  5  2 
The 3rd row show the number of Termites in
each IQ range.
The 4th row shows the numbers of people we would expect to
find in each IQ range in such a large population
While there was an appreciable
amount of shifting in the IQs of the Termites as they grew to adulthood, the
maximum downward shift that occurred was 28 points (on the part of 1 male), from
a childhood deviation IQ of 132136 (ratio IQ of 136140) to an adult
deviation IQ of 104108. There were 2 males, presumably originally in the
132136 range in 192122, who scored in the 108112 range on the adult test,
while 19 additional males who placed in the 112 to 116 range as adults. It's
easier to have a badhair day and make a lower score on an IQ test than it is to
accidentally make a higher score on an IQ test, so I'm supposing that the
maximum upward shift among the Termites as they grew to adulthood was no greater
than 28 points, and was probably less than this. In that case, I think it
unlikely that, among the 260,000 people who were initially screened by Dr.
Terman in 192122, there were many individuals (if any) with IQs above 150 who
weren't Termites.
Now by definition,
in a group of about 260,000 adults we would expect find one person with a
deviation IQ of
171172+, or two persons with deviation IQs of 169170+. Two Termites, both
males, made a raw score of 172 on the CMTA, which, on the basis of my
assumption that these scorers would have a "rarity" of 1 in 130,000,
would translate into a score about 4.375 standard
deviations above the general population mean. If we take a score of (172  2) to
represent 4.375 sigma above the mean, then the standard deviation becomes about
38.857 points. If we use this standard deviation to calculate a score 2.5
standard deviations above the mean (which was the average score of all the
Termites), we arrive at a score of 99... 1 point above
the men's average on the CMTA, and 3 points above the overall average of 96. And we've arrived at this simply by observing
that, by definition, the two brightest people out of 260,000 should fall about
4.375 sigma above the mean.
Seven of the adult Termites had raw scores on the CMTA above 160 on the CMTA.
Using 38.857 for the standard deviation, a raw score of 160 would interpolate to
about 4.066
S. D. above the mean, with an expected frequency of occurrence of 1 in 40,000,
corresponding to a deviation IQ of about 165+. We would therefore expect six scores at this
level or above and instead, there are seven.
Twentyone of the adult Termites had raw scores of, or above,
150 on the CMTA.
This corresponds to about 3.8 standard deviations above the mean, with an
expected frequency of occurrence of 1 in 14,000, or an expected complement of 19 individuals
(compared to 21 obsaerved).
Fortyfive of the adult Termites scored at or above a CMTA
raw score of 140,
corresponding to a frequency of about 1 in 5,000, or an expected occurrence in
this size population of
about 51 (comparted to 45 observed).
We're now getting down into a scoring range in which the fact
that we're dealing with only 954 of the original 1,528 Termites is showing its
effects. But the principal source of this divergence in the numbers arises
because the Termites were originally chosen because they all had IQs above a
threshold value of something like 140. Now, though, on the CMTA, they exhibit
an average IQ of 140. While the highest IQs in the group may still reach 170 (or
so I'm assuming), their lowest IQ scorers fall into the IQ 104108 range. (The
distribution of scores among the Termites is bellshaped around 136  140
StanfordBinetwhereas
before, it had a sharp lower cutoff at 136.)
Ninetyseven of the Termites scored 130 or above on the CMTA. About 130
individuals would have been expected to score at this level or above, if we had
had the full 1,528 Termites available to take the CMTA.
One hundred fortythree scored 120 or above (deviation IQ 0f
144).
About 325 would have been expected to score this high out of the original group
of Termites. We would have expected the 143 scoring above 120 had the rest of
the original cohort been available to take this test. The difference between 325
and 225 probably represents the Termites whose IQs have slipped below 144 as
they grew into adulthood. Some part of this may represent the genderspecific
decline in IQs as girls grow into womanhood.
This seems to suggest that a standard deviation of about 38.8
points of raw score fits the observed scores well, although we can't say much
about what happens at the lower scoring levels without having the full original
group present for these measurements, and without addressing the diffusion of
adult IQ scores below the childhood deviationIQ threshold of 136.
So what would be the ceiling on this test? About 4.84
standard deviations, or about an IQ of about 177.5. However, ceiling effects
would undermine its effectiveness well below that peak possible score.
Comparing the CMTA IQ Scores of the Adult
Termites with Their Childhood StanfordBinet IQs
In converting
the Termites' StanfordBinet IQs to deviation IQs, I used the Termites' own
data, as opposed to applying a lognormal model. Since deviation iQs are defined
in terms of percentiles, the Termites' inferred deviation IQs are the IQs that
would be associated with given percentiles if the distribution of IQs were
Gaussian. What's startling about this chart is the way so many of the Termites'
IQs have migrated below the 136 (SB IQ of 140) cutoff IQ that originally got
them into the Terman Study. It looks as though, as adults, nearly half of them
wouldn't qualify for the 136deviationIQ (top 1%) entry level for the study.
Since these are deviation IQs, the distribution for the total populace can't
change. That means that for every Termite who migrated below the deviationIQ
threshold as they grew up, there must have been another child in the same
population of 260,000 school children who moved up to take his or her place.
Otherwise, the shape of the distribution for the whole population would have
changed at the top end.
There is one other possibility, I suppose, and that is that
the surplus of very high IQs thins out as children reach adulthood. This could
account for regression to the mean, and for the highly nonGaussian (e. g., lnnormal)
nature of children's IQs, a condition which would than disappear when the
children reached adulthood.
A previous discussion of this topic may be found here.
Two very busy
tables may complement the above graph.
Tables I and II below show the amount of regression to the
mean that has occurred between the times the Termites were first tested in
childhood, using the StanfordBinet, and the time they were tested as adults
using the Concept Mastery Test (CMT)  A.
Table I  StanfordBinet Table II  Childhood
Deviation
IQs and their Equivalent IQs vs. Adult CMT IQs, and
Deviation
IQs
the corresponding declines.


The first column
in Table I presents a set of childhood StanfordBinet IQs. The second column
consists of the equivalent childhood deviation IQs that would go with the
frequencies observed with the 260,000child Terman testing population. Column 3
gives the childhood deviation IQs predicted by a lnnormal distribution,
in order to provide some independent measure of the appropriateness of these
Termanderived deviationIQ assignments. What these numbers show is that the IQs
of the Termite children were considerably lower if measured on a deviationIQ
scale than they would be on a StanfordBinet scale. (Note that column 2 has been
generated without any assumptions regarding possible relationships between
deviation IQs and StanfordBinet ratio IQs. It's based upon strictly empirical
numbers.)
The first column in Table II contains the number of Termites
who had childhood StanfordBinet IQs given in column 1 of Table I. For
example, 22 of the Termites who took the CMTA in 1940 had childhood StanfordBinet
IQ scores between 135 and 140, corresponding to childhood deviation IQ scores
between 132 and 136, with an assumed average deviation IQ of 134.
The second column in Table II gives the average score this
group made as adults in 1940 on the CMTA. for our example, the 22 adult
testtakers scored 84.5 correct answers on the CMTA.
The third column in table II set forth the estimated average
childhood deviation IQ for each group.
The fourth column gives the adult deviation IQs corresponding
to the mean CMT scores in column 2, assuming that a score of 98 is 2.5 standard
deviations above the population mean of 2. For our example, a score of 84.5 is
about 13.5 points of raw score or about 2.1625 standard deviations above the
mean, leading to an adult deviation of about 134 (standard deviation = 16).
The fifth column contains the decline in IQ from childhood to
adulthood. Since all these scores are deviation scores, these declines are real.
The
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 CMTA
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 192122. I have truncated the Gaussian
distribution so that it show no scores below deviationIQ = 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 randomlyselected 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 randomlyselected 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
CMTA in 1940. Table 1 shows the data in Figure 2.
CMT Score  10  20  30  40  50  60  70  80  90  100  110  120  130  140  150  160  172 
IQ Range 
104  108  112  116  120  124  128  132  136  140  144  148  152  156  160  164  168 
Termites  1  2  19  13  35  30  49  60  51  64  60  46  52  24  14  5  2 
Gaussian  11,500  11,000  9,000  6,800  4,900  3,800  2,300  1,300  820  434  196  111  36  20  12  5  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 notassmart 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 StanfordBinet/136
deviationIQ threshold for the Terman Study. Perhaps, a fifth of the Termites
fell far enough below the threshold that mere testretest 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 testretest 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
testretest and crosstest 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.