About Confidence Interval
A confidence interval gives an estimated range of values which is likely to include an unknown population parameter, calculated from a given set of sample data.
How It Works
This calculator uses the standard formula for confidence interval: CI = mean ± Z * (σ/√n). The Z-value depends on the confidence level you select.
Interpretation
A 95% confidence interval means if you repeated the experiment many times, approximately 95% of the calculated intervals would contain the true population mean.
Advice
Ensure your sample is random and independent. Larger sample sizes reduce the margin of error and make the interval more precise.
FAQs
What if the sample size is small? You should use the t-distribution instead of Z for small samples.
Can I use this for proportions? No, this calculator is for means. Use a proportion CI calculator for percentages.
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