Question

question 18 1 pts ch 9 the purpose of blocking is to control the effects of an outside variable that is not of interest to the researchers. ensure that the results from an experiment are accurate. arrange experimental units according to similarity.

Explanation:

In experimental design, blocking is used to control the effects of a confounding variable (an outside variable not of interest) to reduce variability and make the experiment more precise. The first option correctly describes this purpose. The second option is too vague as accuracy is a broad term, and blocking's main role isn't just general accuracy. The third option describes grouping (like in blocking but the purpose of blocking is about controlling extraneous variables, not just arranging by similarity).

Answer:

A. control the effects of an outside variable that is not of interest to the researchers.