[epistasis]

For a publishable effect at smaller n, the effect size needs to be fairly large. If you have a huge number of people in a trial, you can get statistical significance of negligible consequence.

The problem with a single study of n=50 isn't the 50, it's that it's a single study.

[jbullock35]

That's not quite right. If the study is underpowered at n = 50 --- which is extremely likely --- statistically significant estimates are likely to be inflated. And as power declines, they also become more likely to have the wrong sign (e.g., the study will yield a positive estimate even though the true effect is negative).

See https://doi.org/10.1177/1745691614551642.