One year ago, in Noesis #125, I presented a table of comparative statistics on high scorers on the LAIT and the Mega Test, introduced by this paragraph:
I have examined much of the available data on the tests we accept. Here are statistics on the highest scores on the LAIT (from Sigma Four #5, January 1980; out of 15,000 testees) and the Mega Test (sixth norming report, May 1989; out of 3920). The [seventh] column shows the number of Mega testees at each level per 15,000, to facilitate comparison. As about 27,000 people have taken the LAIT, I estimate that the current totals are about twice the figures for this early sample.
My original table had only five columns. I have added three more columns to facilitate comparison between the two distributions. Two of the columns added show cumulative totals for the LAIT and the Mega Test.
The mean score for the LAIT sample was 2.84 sigma, approximately one in
495. The mean score for the Mega sample was 3.26 sigma, approximately one in 1735. In
order to estimate the number of very high scores to be expected in a Mega sample of the
same size as the LAIT sample (15,000) if the tests were of equal difficulty, the
cumulative number for each LAIT score was adjusted by 1735/495 = 3.5 (shown in the third
added column). Columns 4 and 8 are most directly comparable.
Mega Test (N=3,920)
|I.Q.||Number||Cum.||X 3.5||Raw||Number||Per 15K||Cum.|
The similarity of the distributions is obvious--and to be expected, given that both samples were predominantly composed of Omni readers. The Mega Test has a slightly higher ceiling than the LAIT. There is a further question regarding the general population percentile corresponding to each score. My norms place the ceiling of the LAIT at 176; my study of Ron's data placed the ceiling of the Mega Test at 178; Ron contends that the ceiling is as much as ten points higher than this. If Ron is right, it follows that the ceiling of the LAIT is much higher than 176.
In my opinion, it's stretching things considerably to claim that these tests are accurate at their ceilings or a couple of points below them. The one-per-million level occurs at 176 on the LAIT and 46 on the Mega. Even if we allow one point for ceiling bumping, fewer than fifteen people have made scores this high on my tests or Ron's. I suggest that we lower our percentile cutoff to 99.9997, one in 300,000, 4.5 sigma, Mega/Titan 43, LAIT 172. Other views are invited.