Sample Size Calculator
Determine how many responses you need for statistical significance.
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Formulas
n = Z²p(1-p) / E²Use p=0.5 if unknown (most conservative).
Sample Size
Z-scores: 90% = 1.645. 95% = 1.96. 99% = 2.576. At 95% confidence, 5% margin: need 385 responses. At 99%, 3%: need 1,844.