Exercise

# Running a simple bootstrap

Welcome to the first exercise in the bootstrapping section. We will work through an example where we learn to run a simple bootstrap. As we saw in the video, the main idea behind bootstrapping is sampling with replacement.

Suppose you own a factory that produces wrenches. You want to be able to characterize the average length of the wrenches and ensure that they meet some specifications. Your factory produces thousands of wrenches every day, but it's infeasible to measure the length of each wrench. However, you have access to a representative sample of 100 wrenches. Let's use bootstrapping to get the 95% confidence interval (CI) for the average lengths.

Examine the list `wrench_lengths`

, which has 100 observed lengths of wrenches, in the shell.

Instructions

**100 XP**

- Draw a random sample with replacement from
`wrench_lengths`

and store it in`temp_sample`

. Set`size = len(wrench_lengths)`

. - Calculate the mean length of each sample, assign it to
`sample_mean`

, and then append it to`mean_lengths`

. - Calculate the bootstrapped mean (
`boot_mean`

) and bootstrapped 95% confidence interval (`boot_95_ci`

) by using`np.percentile()`

.