Sample Size Calculator

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Determine how large of a sample you need to get an accurate representation of the overall population of the group you are targeting. For terminology and an explanation of how sample size and confidence intervals are calculated, click here.

Sample size terminology

• Confidence level
  The confidence level tells you how "sure" you can be that your population would pick a certain answer.
• Confidence interval
  The confidence interval is the +/- range that is added to the answer you receive from your sample to provide a percentage range that accurately describes the likely answer of the population.
• Population
  The larger your sample in comparison to the overall population, the more accurate your answers will be. However, if the population is very large or unknown, you can leave this blank as, mathematically speaking, the differences are statistically minimal.

For example, if you sample 1,000 people with a confidence level of 95% and a confidence interval of 3, and 70% choose Brand A, you can be 95% certain that 67%-73% (70% +/- 3) would choose Brand A.

Confidence level terminology

• Sample size
  The sample size is the chunk of people you have chosen to survey from a larger population. The larger your sample in comparison to the overall population, the more accurate your answers will become.
• Percentage
  This is the percentage of your sample who answered a specific way. If 90% of your sample chooses Brand A, you can be pretty sure that the population would choose Brand A, whereas if 51% of your sample chooses Brand A, the likelihood that this is incorrect is higher. Essentially, you can be more confident in extreme answers rather than middle-of-the-road answers. Keep at 50% to get the most usable confidence interval.