> From: "Joe Weinstein" <[EMAIL PROTECTED]> > Date: Thu, 20 Nov 2003 00:10:11 -0800 > Subject: [EM] CONFIRMATION SAMPLE SIZE > > CONFIRMATION SAMPLE SIZE (WAS Re: Re: Touch Screen Voting Machines) > > THE QUESTION. In EM message 12737, Wed. 19 Nov 03, Ken Johnson asked: > > "Suppose you have a two-candidate election with 10,000,000 voters, and > the computer > says that candidate A beats candidate B 51% to 49%. How many > randomly-selected ballots would you need ...to confirm the election > result with 99.99% confidence?"
Thanks for doing the calculation. I was thinking of replying to this post. It's a good thing you did because I think I definitely would have done a completely wrong statistical test. You made a case for saying that for the above election, it would be better to have approximately 150,000 randomly chosen people to vote in this situation rather than get people to voluntarily vote. My thinking was if the result is going to be a landslide (i.e. A = 1, B = 0), why bother having 150,000 randomly chosen people? Why not add one person at a time until the required accuracy is obtained? I completed my own calculations but then noticed I made a mistake. I forgot that take into account that the standard deviation S = SQRT (X(1-X)/N) (i.e varies with X). As A = 1, therefore X = 1. This makes the S = 0. And this is where I get stuck. So, what should the expression be for N (the required number of voters) given that the election is a landslide? I thought of using the Binomial distribution, but I don't think that's right. Thanks, Gervase. ---- Election-methods mailing list - see http://electorama.com/em for list info