Confidence Interval Calculator
Calculate confidence intervals for common estimates used in clinical and academic research.
About this method
A confidence interval gives a plausible range for the true population value. Narrow intervals indicate more precise estimates; wide intervals indicate greater uncertainty.
Frequently Asked Questions
What does a 95% CI mean?
It means that repeated studies using the same method would produce intervals containing the true value about 95% of the time.
Is confidence interval better than p-value?
They answer different questions. CIs show precision and plausible effect size, while p-values test compatibility with the null hypothesis.
Why is my CI wide?
Wide CIs usually result from small samples, high variability, or rare outcomes.