Question

A study is conducted to determine whether people learn better with spaced or massed practice. Subjects volunteer from an introductory psychology class. At the beginning of the semester 12 subjects volunteer and are assigned to the massed-practice condition. At the end of the semester 12 subjects volunteer and are assigned to the spaced-practice condition. This experiment involves two kinds of non-random sampling: (1) Subjects are not randomly sampled from some specified population and (2) subjects are not randomly assigned to conditions. Which of the problems relates to the generality of the results? Which of the problems relates to the validity of the results? Which problem is more serious?

Answer 1

Answer and Step-by-step explanation: In the study conducted, the problem that relates to generality of the results is (1) the subjects are not randomly sampled from some specified population, because it can't produce results that is for general population. It would be biased since the sample is taken by a volunteer group.

The problem related to validity is (2) subjects are not randomly assigned to conditions. It is not possible to determine the relationship among variables, since sampling can be biased.

from the two problems, the problem related to validity is more serious because it affects the credibility of the study, rather it's reliable or not.