Something like this, any sample size 300 or above (assuming it was drawn in a representative way) is generally regarded as legit.
Source: I run and analyze surveys for a living
Source: I run and analyze surveys for a living
Look at one high school, then another. Take each high school from opposite ends of the country. Same results? Not sure about that. But hey, magic number says we’re all good. Run the article, right?
Would you think it was any better if it was 3000 people from the same area rather than 300? Probably not a lot.
If you pick 300 or more random people throughout the country, you've going to get a pretty accurate representation of the average person.
AmeriSpeak seems to have national representation, so I can only assume it was drawn randomly throughout the nation.