Given Information:12-week clinical trial of a new painkiller.
Nearly all patients completed the full dosing schedule without interruption.
Researcher's conclusion: The drug had little positive effect since the average reduction is pain scores across the data was only modest.
We need to find an option that weakens the researcher's conclusion i.e., prove that the drug did in fact show promising results, so let's weigh each option:
A. This option says that the painkiller worked better on some than others but it doesn't prove that the positive effect was significant overall.
Eliminate.
B. The passage already mentions that almost all patients completed the full dosing schedule without interruption, so the few patients that didn't are merely outliers and don't have significant impact on the results. Hence,
eliminate.
C. If anything, this strengthens the researcher's finding, since the placebo (i.e., fake medicine) provides the same amount of relief as the painkiller which means the painkiller isn't all that effective. Hence,
eliminate.
D. This option seems promising since the negligible pain score reductions over the first two thirds (8 weeks) of the trial could skew the results towards the lower end even if there was substantial improvement in pain scores in the last 4 weeks (only one third of the duration) of the trial.
Keep.
E. This option simply implies that all the drugs in the market treating the chronic pain condition in question have showed modest average reductions in pain scores which doesn't really have much to do with the efficacy of the drug in
this clinical trial. Hence,
irrelevant.
Therefore, our best bet is
option D.