Your Doctor says: " Drinking one glass of red wine per day regularly reduces the chances of getting heart disease." There are two ways to study this claim.
I.) Find 150 individuals who drink red wine regularly and follow them for 20 years.
II.) Find 120 individuals and have 60 of them drink 1 glass of wine per day, and the other 60 not drink any wine. Follow them for 15 years.
Which design is more trustworthy and why?
I would say that design number I is more trustworthy for a few reasons...
a.) Law of Large Numbers
b.) It would be hard to make sure that someone drank a glass of wine everyday for 15 years.
Does my reasoning seem correct? Any other ideas/reasons?