Why has the ratio method of computing IQ been replaced by the deviation method?
A) The deviation method accommodates the fact intelligence does not keep increasing at the same rate as chronological age throughout adulthood.
B) The deviation method is less culturally biased than is the ratio method.
C) Newer tests have made the ratio method of computing IQ obsolete, since the number of questions answered correctly is no longer an important consideration in determining a person's intelligence.
D) Computers can now automatically score tests so the computation of mental age can be done much faster.

Question

Quizplus · Accepted Answer

The problem with using the ratio method of IQ is that intelligence levels off in adulthood (e.g., an average 30-year-old would perform about the same as an average 50-year-old). If mental age remains the same, but is divided by increasingly large chronological age, IQ becomes smaller, even though the adult does not become less intelligent with age. (For example, if the people above both have a mental age of 30, the 30-year-old's ratio IQ would be 100; the 50-year-old's ratio IQ would be 60.) As intelligence testing became useful for adults, a different method of computing IQ needed to be developed.

Why Has the Ratio Method of Computing IQ Been Replaced