# How do you calculate a confidence interval?

To calculate the confidence interval, you need to know:

- The point estimate you are constructing the confidence interval for
- The critical values for the test statistic
- The standard deviation of the sample
- The sample size

Then you can plug these components into the confidence interval formula that corresponds to your data. The formula depends on the type of estimate (e.g. a mean or a proportion) and on the distribution of your data.