Demography

Standard Deviation and Stable Genius

About three thoughts came together and gelled last week.  One was a headline that explained voter turnout in Wisconsin was 5 standard deviations from the mean.  The other was looking at Trump assessing himself as a “stable genius” and Biden’s frequent challenge of having a high IQ.  I realized that I don’t have to explain how to calculate a standard deviation – there is a chart that shows it all in terms of IQ, and it really simplifies matters. 

If you look at the linked table, on the scale that accepts 15 points as the standard deviation, an IQ score of 175 is 5 standard deviations above the norm.  To make that statement understandable, that’s one person out of 3,483,046.  Chances are that I have never met one, despite a career in science and the academy. 

Nasim Taleb writes “IQ” is a stale test meant to measure mental capacity but in fact mostly measures extreme unintelligence”, so let’s look at the IQ 25 – whom I also haven’t met.  0.0000287105% of the population would score below this mark.

Tierman’s classification for genius (based on a standard deviation of 16) was 140 and over – so if you check the chart, that’s one out of every 161 people.  Statistically, we should have four or five living within the Trego school district boundaries.  I don’t know what it takes to be a stable genius – maybe a horse?

IQ RangeClassification
140 and overGenius or near genius
120-140Very superior intelligence
110-120Superior intelligence
90-110Normal or average intelligence
80-90Dullness
70-80Borderline deficiency
Below 70Definite feeble-mindedness
Table developed by Tierman, source: IQ Comparison

When we look at Biden’s quote, “I think I probably have a much higher IQ than you do, I suspect.” and look at the chart in Talib’s paper, toward the bottom we see the range for “legal professions”.  Talib’s comment at the bottom is just as valid for attorneys as college professors.  It does add a bit of perspective.

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