confidence interval calculator
Confidence Interval Calculator: 95% Example Guide
Confidence interval reporting is essential in research and survey work. This article gives a practical 95% CI workflow.
How to calculate using Confidence Interval Calculator
- Provide sample mean, standard deviation, sample size, and confidence level.
- Compute standard error and margin of error.
- Report lower and upper confidence bounds together.
Confidence Interval Calculator formula
- Standard error = sigma / sqrt(n).
- Margin of error = z x standard error.
- Confidence interval = mean +/- margin of error.
Worked example
- Mean 50, SD 10, n=100, 95% confidence (z=1.96).
- SE = 1; margin = 1.96.
- CI = [48.04, 51.96].
Accuracy and interpretation notes
- Use correct critical value for selected confidence level.
- For small samples with unknown sigma, t-interval is often preferred.
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