Study of statistics regarding I.Q. scores in the world and of received test submissions has led the Psychometitor to conclude that the actual level of one in a billion of the world population occurs between I.Q. 180 and 185 (on the commonly used scale with 15 points per standard deviation) rather than at the theoretical 190 where it lies according to the "normal distribution". This is so because the world average I.Q., projected onto this scale, is not 100 but somewhat below 90, probably between 85 and 90. The crux is that the I.Q. scale we use in actuality refers only to the adult populations of Western countries such as those in Europe and North America, and is not correct for the rest of humanity.
For consistency though the Psychometitor has decided to keep the pass level at its original height rather than lowering it to its proper value. This means the admission requirement is more stringent than originally claimed by the society, and the current members have met this more stringent requirement. In fact, this admission level lies well outside the range of scores that can be statistically expected given the world intelligence distribution (the world's highest I.Q. is probably around 185). But since the norms at this very top of the range are tentative - sometimes too high, sometimes too low, searching for their true value - it can be expected every now and then a candidate will qualify. To date, about twelve have qualified out of approximately 3000 who took tests scored by Paul Cooijmans, and 0 have qualified scored by others.
The uncertainty of the norms in this range means that the world's most intelligent persons are not necessarily found in the Giga Society; the actual I.Q.'s of the members, as assessed by the best tests and norms, vary between approximately 140 and 185, the bulk of them being over 160 though. For information about the truly most intelligent - that is, the highest scorers based on the best norms and best tests according to the most recent insights - see the report Statistics of the top scorers.
Many think the Giga Society can only have eight members as a result of its admission level and the size of the world population. This is false. The top eight are not the same individuals at each moment but are being replaced constantly. And as existing members who qualified honestly are not expelled when they are no longer among the top eight, a multiple of that number of members is possible over time.
In addition, tests do not intercorrelate perfectly, although they intercorrelate positively; with a typical correlation of .7 between tests, one is, over multiple tests, selecting about 150 % of the number one is selecting on each individual test, which means that at any given time about twelve persons could theoretically qualify. On the level of members, this imperfect correlation allows for different aptitude profiles to enter.
Another way to look at it is to observe that, on average, 5 candidates per decade have entered so far. At this rate, and considering the life expectancy and the fact that one most likely qualifies beyond age sixteen, so that on average one in about 6.5 members die per decade, straightforward arithmetic shows it will stabilize around 30 members in the 2130s.
Some think the Giga Society's members must be proportionally divided over the continents. This fallacy results from the prejudice that average and spread of mental ability are identical everywhere in the world. But the Giga Society has no prejudice, goes exclusively by test scores, and is blind to a candidate's continent of origin.
As an aside, the member list is not public, so those speaking about the origin of the members may be misinformed to begin with. Possible Giga Society member lists one may find on the Internet should not be trusted, and to know if someone who claims to be a member is an actual member one should contact the Psychometitor for verification (only with express permission of the supposed member). In particular, one must be careful with information found on do-it-yourself online encyclopaedias, as a tendency can be observed for narcissists and megalomaniacs to write themselves on the member list.