[jessriedel]

IQ is just defined in terms of standard deviations. Having an IQ of 130 means you are 3 standard deviations smarter than average, i.e. in the 99.7th percentile. Presumably, they just put Motzart in the top 99.xxxxxx% percentile by guess and calculated the resulting IQ.

[laxatives]

Well calculating using a guess is no better than just starting or ending with a guess

[jessriedel]

Oh sure. I was just clarifying how they went about giving Motzart a number without administering a test.

[kiiski]

Of course you have to remember that different tests use different standard deviations. For example, Mensa here in Finland uses a test with standard deviation of 15, so 130 is "only" two standard deviations smarter than average. The point is, the scores are meaningless without knowing the standard deviation used.

[SiVal]

IQ tests are normed for a standard deviation of 15 points, not 10. (And I'll bet you knew that but got distracted by the '3' in 130. The "D'oh! Effect" -- a side effect of our associative memory architectures.)