You know, I’ve tended to follow the consensus that 15 points is a standard deviation, in intelligence, but that doesn’t help so much because group standard deviations appear to range from 11 to 13, with 12.5 as the sort of median. Secondly, I’ve followed the convention of the center being 100.

Both of these are kind of obscuring value.

1 – the sort of middle between expensive to train and inexpensive to train is actually 106. (I sort of think of human potential beginning in that area.)

via Lion:

*—“A verbal IQ of about 106 defines the cognitive lower bound of the smart fraction. And, each percentage point increase in the “smart percent” is worth about $600 (1998) to per capita GDP.”—*

2 – Every six points (about half a standard deviation) rather than seven, we see fairly rapid increases in ability.

3 – They suggest average is sort of 95-105, and that’s true, but that’s the arbitrary average of the population given the population. Instead, I would say the average begins at 105 or 106 (105 for simplicity’s sake), and that we are one half standard deviation below the minimum for the upper half to compensate for the lower. And one standard deviation or 12 points below the low end of the optimum for modernity. And that this minimum will increase from 112 to 118 over the next century (or faster).

4 – Roughly speaking 1/3 of the population, meaning the vast majority of the population under 95 has to disappear over the next few hundred years.