What three key numbers are needed to calculate sample size?

1. The confidence level desired: The confidence level desired is typically expressed as a percentage, and indicates how certain you are that your sample will represent the population accurately. 2. The margin of error: The margin of error is typically expressed as a percentage, and indicates how precise you want your results to be. A higher margin of error means that you are willing to accept a lower degree of accuracy in your results. 3. The population size: The population size is the total number of individuals in the group you are interested in studying. Knowing the population size will help you calculate the sample size needed to meet the desired confidence level and margin of error.