About Sample Size
When conducting research about your customers, patients, or products, it's usually impossible to collect data from every single person or item. Instead, you select a sample. The sample size is the number of individuals in a sample.
Key Terms
- Confidence Level: The probability that your sample accurately reflects the attitudes of your population. The industry standard is 95%.
- Margin of Error: Also known as the confidence interval. It tells you how much you can expect your survey results to reflect the views of the overall population. e.g. If you have a 5% margin of error and 50% of your sample answers "yes", you can be 95% confident that between 45% and 55% of the total population would answer "yes".
- Population Proportion: The accuracy of the sample size calculation also depends on the percentage of your sample that picks a particular answer. If you're unsure, use 50%, which gives the largest sample size (most conservative).