Process
How to choose your survey sample size in 5 steps
A five-step process for setting a survey sample size before you write a single question. It starts with the decision the result will drive, then the population, the confidence level and margin of error, the group comparisons you need, and how many invitations to send to land your target. Use it with the standard formula, which gives 384 responses for 95% confidence and a 5% margin on any large population.
Where this appears
What's in this process
- Write down your decision: What will you do differently based on the result? If nothing meaningful changes, you need fewer responses.
- Identify your target population: Who exactly you want to learn about. It changes both the formula and how you recruit.
- Pick confidence and margin of error: Defaults are 95% confidence and a 5% margin of error. Only move off them with a reason.
- List the comparisons you need: Every group you compare needs its own sample size, not a slice of one total.
- Plan invites for 3 to 5 times your target: Allow for response rate, screening drop-off and responses you remove for quality.
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<a href="https://www.koji.so/visuals/how-to-choose-survey-sample-size-five-steps"><img src="https://www.koji.so/visuals/how-to-choose-survey-sample-size-five-steps/how-to-choose-survey-sample-size-five-steps.png" alt="Process in five steps for choosing a survey sample size: name the decision, define the population, set confidence, list comparisons, plan invites." width="1200" height="792" /></a>
<p>Source: <a href="https://www.koji.so/visuals/how-to-choose-survey-sample-size-five-steps">How to choose your survey sample size in 5 steps</a>, Koji</p>
