In a study of the effect of color on productivity, 50 of 100 factory workers were moved from their drab workroom to a brightly colored workroom. Both these workers and the 50 who remained in the drab workroom increased their productivity, probably as a result of the interest taken by researchers in the work of both groups during the study.
Which of the following, if true, would cast most doubt upon the author’s interpretation of the study results given above?

Question

Examsnet · Accepted Answer

Correct Answer is :  Many of the workers who moved to the brightly colored workroom reported that they liked the drab workroom as well as or better than they liked the brightly colored workroom

GMAT Verbal Reasoning Practice Test 5