Question

The difference between before-after and controlled before-after experimental design is that the _____.

A. controlled before-after design is meant specifically for primary research

B. before-after design is meant specifically for primary research

C. controlled before-after design involves not one group, but two

D. before-after design eliminates the possibility of other variables influencing the results

E. before-after design measures the variables to be tested before the experiment begins

Answer

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