kamalakarthi wrote:Hi, This question is from Veritas Prep question bank.

In this question, can you help me understand why option E is not correct. My line of analysis.

Conclusion ::There must be something qualitatively different b/w 2 types of mem loss.

Strengthen ::Something should say that fundamentally something is different.

I thought since age is different, the results are different. What am I missing in bigger picture ? Can you please help.

The problem is that we want to know whether there's a difference in the type of brain impairment. Knowing that there's a difference in age between the two groups doesn't tell us this. (And the age gap is something we likely could have surmised on our own. People who are diagnosed with Alzheimer's tend to be older than people who suffer brain injuries from car crashes or high-impact sports.)

Think of it this way: the study is suggesting that the two groups are fundamentally different. If we want to strengthen the conclusion we're deriving from the study, we want it to be the case that the study was well-conducted. In other words, we don't want to have to worry about confounding variables. If for example, Person A suffers from early-stage Alzheimer's and has mild memory impairment and Person B was just in a devastating car wreck and suffered a severe traumatic brain injury, the fact that the drug worked for Person A and not for Person B wouldn't tell us whether the drug works better for Alzheimer's than it does for acute injuries. It would simply confirm that Person A came in with a less severe condition that was more amenable to treatment. So that's the big issue: was the drug tested on subjects who had similar memory impairment.