[kevin_thibedeau]

> I bet many would think n=100 would be worthless once the population reaches millions, or especially billions.

That depends on a uniform distribution of the population and an unbiased sampling method. One of the polls in the 2016 US presidential election [1] would shift Trump's position by a full percentage point based on input from a single man depending on which week he participated in the panel.

[1] https://www.nytimes.com/2016/10/13/upshot/how-one-19-year-ol...

[rcxdude]

Yes, but if your sampling is biased then the solution is not simply a larger sample size. The only way in which larger sample sizes help is giving more power to any methods you use to try to control for sampling bias.

[Dylan16807]

> a full percentage point

If your goal is to be within 10%, that's not a problem.