Shaded area represents the 95% confidence interval around the sample mean.
About this calculator
Overview
A confidence interval is a range of values that is likely to contain a population parameter with a certain level of confidence. It provides a measure of uncertainty about a sample estimate.
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Pro Tips
Ensure your sample is randomly selected and representative of the population.
The Z-distribution is used for large samples (n > 30) where the population standard deviation is known or well-estimated.
If you repeated this experiment 100 times, the true mean would fall within a 95% interval approximately 95 times.
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Fun Facts
"Sir Ronald Fisher popularized the 95% confidence level because it roughly corresponds to two standard deviations from the mean."
"A higher confidence level will result in a wider interval, as you need to be more certain to include the true parameter."
"Increasing the sample size narrows the confidence interval, making your estimate more precise."
