**Link**: Stats

## What is confidence intervals?

A value to quantify the confidence level in the estimated parameters.

95% confidence intervals in Bootstrapping: is an interval that covers 95% of the means.

Note: there are many ways to calculate confidence interval, and bootstrapping is just one of them which we use in here as an example.

## Why are confidence intervals useful?

Anything outside of confidence interval is less than 5%. So the P-value of anything outside of confidence interval is <0.05.

### Use confidence intervals to compare two samples

The verticle lines in this chart represents the many different means in bootstrapping. The horizontal black line represents the 95% confidence interval that covers 95% of the means.

When the 95% CI do not overlap, we can say there is a statistically significant difference in the weight of femal and male mice, aka we know the p-vale is < 0.05.