IQ tests have reliability of 0.9-0.95 and are the sole proxy for IQs over 150. ACT/SAT correlate at 0.75-0.85 with IQ but cap estimates at 142. GPA correlates 0.54-0.69 with IQ – perfect 4.0 GPA averages 125 IQ. Education correlates 0.5-0.6 with IQ – top STEM PhDs average under 135. Highest profession IQs are 118 for electrical engineers or 120-130 for lawyers/doctors. World's most competent workers average 145 IQ assuming 0.5 job performance correlation. US elite scientists average 150 IQ. Income, net worth, occupational attainment correlate too weakly at 0.15-0.5 for high IQ estimates. Personality traits like openness correlate only 0.1-0.3 with IQ. Schizophrenia correlates -0.25 with IQ. Cox's 1926 genius IQ estimates are intuition-based and dubious – philosophers average 180 IQ. Simonton's president IQ methods yield wild discrepancies like Clinton 136-159. Author estimates align on Bush IQ but diverge sharply on JFK/Nixon by 17-27 points. JFK mediocre student yet ranked above striver Nixon shows bias. Voltaire ranked with Newton despite lesser impact. Missing giants like Euler/Gauss indicates flawed lists. Handsome presidents get unfair IQ boosts from electoral advantage.