Sample Size Calculator
Another thing to consider when choosing a sample size is to make sure the sample is from the same population. This can be easy to choose if you were trying to study how tall sunflowers grow, but other times decisions might need to be made to decide what constitutes a population. This is another area to watch to ensure accurate results. A person would also want to make sure the sample size is not being affected by any bias. In political surveys one must be careful to not have a sample of the population in certain geographical or economical locations alone, but would need to get a broad sample to ensure greater accuracy.
This sample size calculator can help you determine what sample size is appropriate depending on how accurate you want the results to be and how large the population. To use the sample size calculator simply select the confidence interval and the confidence level you want. Then enter the population and the calculator will do the rest.