Confidence Interval Calculator
Calculate the confidence interval for a sample mean or proportion. Determine the margin of error for your data set.
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Upper Bound
Margin of Error
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Confidence Interval Calculator
In statistics, a confidence interval (CI) is a range of values that is likely to contain a population parameter. The most common is the 95% Confidence Interval, which means if you repeated the experiment 100 times, the true mean would fall within this range 95 times.
The Formula
CI = x̄ ± Z * (σ / √n)
- x̄: Sample Mean
- Z: Z-score for confidence level (1.96 for 95%)
- σ: Standard Deviation
- n: Sample Size
Why it matters
Simply stating an 'average' is misleading without knowing the reliability of that data. A narrow CI indicates high precision (often due to large sample size), while a wide CI suggests the data is noisy or the sample is too small invades certainty.
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Disclaimer
This calculator is provided for educational and informational purposes only. It does not constitute professional legal, financial, medical, or engineering advice. While we strive for accuracy, results are estimates based on the inputs provided and should not be relied upon for making significant decisions. Please consult a qualified professional (lawyer, accountant, doctor, etc.) to verify your specific situation. CalculateThis.ai disclaims any liability for damages resulting from the use of this tool.