A report in a medical journal notes that the risk of developing Alzheimer’s disease among subjects who regularly opted to take the drug ibuprofen was about half the risk of those who did not. Is this good evidence that ibuprofen is effective in preventing Alzheimer’s disease?

a. Yes, because the study was a randomized, comparative experiment.

b. No, because the effect of ibuprofen is confounded with the placebo effect.

c. Yes, because the results were published in a reputable professional journal.

d. No, because this is an observational study. An experiment would be needed to confirm

(or not confirm) the observed effect.

e. Yes, because a $50\%$reduction can’t happen just by chance.

We are given a report of medical journal that the risk of developing Alzheimer’s disease among subjects who regularly opted to take the drug ibuprofen was about half the risk of those who did not.

We need to find out whether is this good evidence that ibuprofen is effective in preventing Alzheimer’s disease and select correct answer from given option.

Because this is an observational study, the answer is no. To validate (or disprove) the observed effect, an experiment would be required. The reason for this is because, whereas experiments can prove cause and effect when done correctly, observational studies can't since there are much too many variables. In observational research, only a correlation between the explanatory and response variables may be shown. As a result, option d is correct option.