If groups are predefined and of interest themselves, the explanatory variable is called a(n) ____ effect, but if the groups are randomly sampled from a population of possible groups, the explanatory variable is called a(n) ____ effect.

Question

Quizplus · Accepted Answer

When groups are predefined and of interest, the explanatory variable is referred to as a fixed effect because the levels of the variable (the groups) are specifically chosen by the researcher and are of direct interest. When the groups are randomly sampled from a larger population, the explanatory variable is considered a random effect, as the levels (groups) represent a random sample from a broader population, and the interest lies in generalizing findings to the larger population.

If Groups Are Predefined and of Interest Themselves, the Explanatory