Social ecology of intelligence and suicide in the United States.

Two proxy variables for regional intelligence, state-level mean scores of 1994-2004 on the American College Test and of 1982, 1993, 1994, and 1998-2004 on the Scholastic Assessment Test, were consistently positively correlated with the averaged regional U.S. suicide rates of 1990-1994. The effects observed in these ecological (group-level) analyses were of small size, with correlation coefficients ranging from .05 to .25, thus mostly falling below the nominal statistical significance level. The present evidence nevertheless adds to several recent findings from international geographical studies by Lester and by Voracek of a positive association of intelligence and suicide mortality by indicating that this pattern may also exist on the within-nation level.