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.