Sample Size
Based on
- the number of people in the sample (or population)
- the number of people who respond
- the response distribution
- e.g., 50% said yes, 50% said no; 90% said yes, 10% said no
- how sure you want to be of you data (confidence interval)
- e.g., a 95% confidence interval means that you can be sure that 95 out of 100 times the responses to a given question would be within some calculable percentage points of the actual number you got.