The strongest studies can find the weakest effects. Imagine some huge and very well resourced clinical trial finds some effect. Millions of participants being tracked and monitored extensively over many years. Everything double blind, randomized ect. Really good statisticians analyzing the results. A trial like this is capable of finding effect sizes that are really really small. It is also capable of detecting larger effects. However, people generally don’t run trials that big, if the effect is so massive and obvious it can be seen with a handful of patients.
On the other hand, a totally sloppy prescientific methodology can easily detect results if they are large enough. If you had a total miracle cure, you could get strong evidence of its effectiveness just by giving it to one obviously very ill person and watching them immediately get totally better.
The strongest studies can find the weakest effects. Imagine some huge and very well resourced clinical trial finds some effect. Millions of participants being tracked and monitored extensively over many years. Everything double blind, randomized ect. Really good statisticians analyzing the results. A trial like this is capable of finding effect sizes that are really really small. It is also capable of detecting larger effects. However, people generally don’t run trials that big, if the effect is so massive and obvious it can be seen with a handful of patients.
On the other hand, a totally sloppy prescientific methodology can easily detect results if they are large enough. If you had a total miracle cure, you could get strong evidence of its effectiveness just by giving it to one obviously very ill person and watching them immediately get totally better.