How can I determine the minimum sample size for a market research?

Question

Is there a table or a simple way to say eg.

If the universe (n) = 10,000 people, i need a sample of X people to get a confidence of +-5%


Thanks!!

Answer 1

If you can establish a relation between the number of people n and the confidence associated with each n, you can solve for n.
This can be achieved if you know the mean, standard deviation etc. The source gives an example, but you need additional information rather than just n=10,000 and error=+-5 %.

Answer 2

Not quite what you describe, but there are tables and figures that you can find in statistical textbooks. The one I remember most is a figure that gives you the certain confidence limits for a binomial probability as a function of sample size.

I don't know your market research, but you may have to take into consideration the "beta" of a test. A successful test should be able to accept the correct hypothesis and also to reject the incorrect hypothesis. Alpha is the first part of this, beta is the second.