For polling to be unbiased, it must be random. That random sample, if done correctly should be equal to race/gender/age % of the population as a whole. Let’s take race as an example. Say the national African-American population is 15%. Picking a random phone number to poll someone, I have a 15% chance of calling an African-American. If Caucasians make up 70% of the national population, I have a 70% chance of calling a Caucasian. So once my total sample has been taken, I should have basically the same percentages. If I call 1,000 people, 700 should be Caucasian and 150 should be African American. The equal representation was based due to the sheer randomness of it.
I’ll give you an example of a biased poll. In 1936, Literary Digest used a mail in sheet to try and determine who would win the election. Over 2 million (!) people responded. This was the first year that Gallup started doing presidential elections. He took a sample of 1,500 people. Who ended up being correct? Gallup, with a sample size of 1,500. The reason is because Literary Digest had a biased sample, less lower class workers subscribed to it, thus neglecting part of the population. Gallups poll was random, ensuring that it was an accurate representation of the population due to its randomness.
if its not 100% there is no way of knowing what the true opinon is. I don’t care if its 10 people from 300 million or 100,000 out of 300 million.
That is obviously true, but the question is what is an acceptable level? Surely polling 300 million people is not feasible. But due to statistical measuring, we can have an answer that is has a 5% chance of error with a much smaller sample size.
No I don’t believe it represents the nation as a whole. Out of 300 million, only 122,229,000 people that were elligible or cared enough to vote, did and thats not even half of the country.
The data could easly be represented to narrow it to only those who voted. I am sure that in these polls the question is also raised if they are an active voter. You can sign up at gallup.com for $95 a year if you are really interested.
I believe that polls are unprecise no matter how well executed or well manored they are ment to be.
What is your definition of precise? What do you feel is an acceptable confidence level?