Value of difficult temperament among 7-year-olds in the general population for predicting psychiatric diagnosis at age 12.

The authors assessed the predictive value of "difficult" temperament, as defined in the New York Longitudinal Study, in 12-year-old children from the general population of Quebec City whose temperaments had been determined to be difficult or easy at age 7. The difficult and easy temperament groups were balanced for age, sex, and socioeconomic status. The authors used many convergent measuring devices and were blind to the temperament scores of the children at age 7.