>>12365689The original "intelligence quotient" purported to calculate the ratio of the "mental age" of a child or young adult to his or her actual age. But that still doesn't mean that 150 was supposed to be "1.5 times as intelligent as" 100. It means that a child with an IQ of 150 was as intelligent as the average child 1.5 times his or her age.
But that was all nonsense anyway, as should be obvious the moment you think about how nonlinear development is. The modern IQ is just a Z-score shifted and scaled to be numerically similar to the old system. Personally, I think it would be a lot clearer if it were just expressed as a percentile, which gives the exact same information. So for instance, someone with an IQ of 100 is at the 50% percentile, and someone with an IQ of 150 is at the 99.6% percentile. That tells you nothing about how much more intelligent the top centile is than the average or anything of the sort. Since we have no way to quantify intelligence, there is no way to measure its variance or any of its other moments.
