I agree. You only multiply the SAT z-score by 0.8 if you’re selecting people on high SAT score and estimating the IQ of that subpopulation, making a correction for regressional Goodhart. Rationalists are more likely selected for high g which causes both SAT and IQ, so the z-score should be around 2.42, which means the estimate should be (100 + 2.42 * 15 − 6) = 130.3. From the link, the exact values should depend on the correlations between g, IQ, and SAT score, but it seems unlikely that the correction factor is as low as 0.8.
I agree. You only multiply the SAT z-score by 0.8 if you’re selecting people on high SAT score and estimating the IQ of that subpopulation, making a correction for regressional Goodhart. Rationalists are more likely selected for high g which causes both SAT and IQ, so the z-score should be around 2.42, which means the estimate should be (100 + 2.42 * 15 − 6) = 130.3. From the link, the exact values should depend on the correlations between g, IQ, and SAT score, but it seems unlikely that the correction factor is as low as 0.8.