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Sample size calculator
How many people do you need to survey?
You need at least 385 complete responses.
At a 30 % response rate, invite about 1,284 people.
What does it mean?
With 385 responses, a proportion you measure (e.g. 40 % agree) lies within ±5 percentage points of the true value with 95 % confidence. 50 % is the most cautious assumption and gives the largest sample.
Learn more
- Sample sizeFor a survey with 95% confidence and a ±5% margin of error you need about 385 responses. For group comparisons, a power analysis sets the size.
- Questionnaire designA good questionnaire starts from your research question, uses validated scales, neutral wording and a logical order, and is pilot tested before launch.
- Sampling methodsProbability sampling gives everyone a known chance of selection and supports generalization; non-probability sampling is quicker but limits it.
- Survey response rateThe response rate is the share of invited people who complete your survey. Short surveys, personal invitations and reminders raise it most reliably.
- Confidence intervalA 95% confidence interval gives a range of plausible values for a population parameter. It shows both the size of an estimate and its precision.
- Type I and Type II errorsA Type I error is a false positive (rejecting a true null hypothesis, risk α); a Type II error is a false negative (missing a real effect, risk β).
