Online courses are as effective as in-person courses, as shown by completion rates.

• A. The measurement only considered short-term retention, not long-term understanding.
• B. The online courses counted only courses with high completion rates.
• C. The exams were designed differently between formats.
• D. The sample size was very small.

Answer: (A)

The key idea is that using completion rates to judge effectiveness assumes that finishing a course equates to learning the material. The best answer points out a flaw in that assumption: if the measurement only captures short-term retention and completion, it ignores whether students actually understand and retain information over time. A course could be completed quickly, but if the knowledge fades, the claim that online courses are as effective as in-person ones isn’t well supported by completion data alone.

If only high-completion courses were included, that would bias the results and distort the comparison, but that isn’t addressing the main issue of what the measure actually reflects. Differing exam designs between formats could complicate comparisons of performance, and a small sample size affects reliability, but neither gets at the core problem that completion rates don’t measure long-term understanding. The takeaway is that to claim equal effectiveness, you’d need measures that assess long-term retention and mastery, not just who finishes.