Sampling Size Calculation Verified ✓

To calculate your sample size, you generally need to plug four specific variables into a formula: A. Confidence Level (Alpha)

For a large or unknown population, use this standard equation: sampling size calculation

This is the "plus or minus" number you often see in polls (e.g., "±3%"). It represents the maximum expected difference between your sample estimate and the true population value. A smaller margin of error requires a larger sample size. Asking for ±1% precision costs far more than accepting ±5%. To calculate your sample size, you generally need

You work for a streaming service. You want to estimate the percentage of users who would recommend your service to a friend. You want 95% confidence and a margin of error of ±3%. You have no prior data. A smaller margin of error requires a larger sample size

Use pilot study data or previous literature to guess what kind of difference you are looking for.