A confidence interval for a population proportion is a range of values that is likely to contain a population proportion with a certain level of confidence.
The formula to calculate this confidence interval is:
Confidence interval = p +/- z*(√p(1-p)/n)
- p: sample proportion
- z: the z-critical value based on the confidence level
- n: sample proportion
To find a confidence interval for a population proportion, simply fill in the boxes below and then click the “Calculate” button.
95% C.I. = [0.4627, 0.6573]
You can be 95% confident that the interval [0.4627, 0.6573] contains the true population proportion.