IQ tests do not yield clinically useful information.

Instead, the cause was likely environmental mproved education, better healthcare, and better nutrition.In the mid-twentieth century,psychologists also attempted to use IQ tests to evaluate things other than general intelligence,particularly schizophrenia, depression,and other psychiatric conditions.These diagnoses relied in part on the clinical judgment of the evaluators,and used a subset of the tests used to determine IQ practice later research found does not yield clinically useful information.