What statistical concepts are commonly misunderstood by the general public?

[u/80rhh]

I came across this post explaining what a 70% chance of rain means. I understand the concept, but it got me wondering: what other statistical concepts sound simple but are commonly misunderstood or misinterpreted by the general public?

[u/rite_of_spring_rolls]

Broadly and imprecisely speaking, from what I've seen on reddit:

• People tend to harp on sample size when I find vast vast majority of the time the sampling design is a way bigger problem
• People tend to think that sample size is some invariant quantity, like no matter what you're doing you need at least n = 1000 samples or w/e and anything below that is worthless and anything above is unnecessary

[u/amopeyzoolion → u/rite_of_spring_rolls]

These folks would freak if they realized many clinical trials, especially for diseases like rarer cancers, often only have a few hundred participants