Hacker News Reader

Doesn't a sample size need to be at least 30 to be statistically significant?

If the effect was detectable in the small sample, in a 8x larger sample it should show up clearly.

If it is a statistical artifact, of course it won't.

P value is a measure of statistical significance. Sample size doesn't matter as much as most believe, as long as your p value is really low.

P values can't save you if the number of diverse subpopulations in the general population is larger than your sample size. Also, they break the two dozen people into many groups, so they've implicitly tested many hypotheses.

Even if they did the stats right, there can be hidden causality at play with samples this small. Maybe 100% of the people that don't eat red meat in their sample grew up in poor households with poor nutrition, or maybe they all live in the arts district, which is close to an industrial polluter.

Anyway, it looks like it is worth further study with larger samples, but I don't think you can draw any actionable conclusions from the current study.

If not several thousand

What is statistically special about 200?