[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.

[kabar]

I took a statistics course in graduate school and learned about how political polls are conducted. There can be randomness within groups, but the groups have to be representative of the total demographic.

If you are going to do a national poll, you don't do a random sample in downtown Chicago.