Individuals with obsessive-compulsive disorder feel a deep sense of relief if they can talk themselves into forgoing a ritual

There is a significant positive correlation between IQ scores and academic performance (grades). Given this statistic, we can reasonably conclude that _______

a. low IQ scores and low grades are not at all related b. high IQ scores are a predictor of good grades c. high IQ scores are the only established cause of high grades d. low IQ scores are a result of neglectful parenting.

Like longitudinal research, cross-sectional studies

A) can be threatened by cohort effects. B) often rely on biased observation procedures. C) can be threatened by selective attrition. D) can be threatened by practice effects.