[jrochkind1]

yup.

If you flip a coin 10 times, there is less than a 5% chance you will get 3 or fewer tails -- so if you do, that looks "statistically significant" that you have a weighted coin (which still doesn't guarantee it).

But if 500 people in different places flip a coin 10 times, what are the chances at least one of them will get 3 or fewer tails? Oops. It doesn't mean your chances of having a weighted coin went up.