Subject variables

Subject variables. Address the difficulty of studying subject variables. To illustrate this, have them suppose that they did a study in which women did better than men on an intelligence test. Before saying that women are smarter than men, the students would have to establish that

  1. their sample of men and their sample of women were representative of the population at large;

  2. the IQ test had construct validity; and

  3. the test had equal construct validity for men as for women.

Furthermore, even if all three points were established

  1. we would not know why women did better than men (heredity, environment), and

  2. the r-squared (coefficient of determination) would probably be small, revealing that very little variability was accounted for by gender.

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