Suppose we want to estimate a sample proportion to within 0.05 with 95% confidence, how large will the sample have to be?
There is no other information about the distributions of the population or the sample.
How do I approach this problem?
See attempted solution below.
for a proportion problem, sample stddev, sigma x bar = sqrt(pq/n)
The Attempt at a Solution
No point in trying to solve for n in the equation 1.96 * sqrt(pq / n) = 0.05, because I don't know what pq is.
(This is NOT homework. I'm a 62 year-old brushing up on statistics for professional reasons, but one of your "mentors" with a bike-riding avatar is worried that I might be cheating on a high school exam, so he sent me here. Maybe I'm in my 2nd childhood, which is why I provoke these suspicions. I got some *great* responses to more difficult statistics problems on this forum back in 2012. I do hope your new policies have not rendered this resource useless to me. I will go bug people on the actuarial forums if you force me to, though I'd rather not because I think this is a more appropriate venue - or used to be, anyway.)