[kabar]

Samples are not done randomly in polling. They are carefully constructed to capture the demographics of the country, state, region, etc.

[jpsb]

Then I took statistics many years ago. I learned that a random sampling of 880 members of any grouping would yeild the percentages of various subgroups. Randomly sample 880 jelly beans in a 300 million jelly bean jar and you will know how many are red, pink, blue etc. I guess things have changed since then (70s). I've forgotten why 880 is the magic number but I do remember it was 880.

[riverdawg]

“Samples are not done randomly in polling. They are carefully constructed to capture the demographics of the country, state, region, etc.”

That’s called stratified random sampling.