Cross-Age Correlations Are Used to Assess the Stability of IQ

Cross-age correlations are used to assess the stability of IQ. Research has shown that IQ is generally

A) highly stable; cross-age correlations with adult IQ are about .70-.80 by 8 or 9 years of age.
B) highly stable, but only for children living in extreme environments (that is, extreme poverty or substantial wealth) .
C) not highly stable; cross-age correlations never exceed .30-.40 when IQ is assessed over a period of two years or longer.
D) not highly stable; IQ is a good predictor of how a person is functioning at a specific time, but is highly variable with situations and thus produces highly different scores when given to the same person at different time, producing cross-age correlations that rarely exceed .30.