Exercise

# Basic jackknife estimation - mean

Jackknife resampling is an older procedure, which isn't used as often compared as bootstrapping. However, it's still useful to know how to run a basic jackknife estimation procedure. In this first exercise, we will calculate the jackknife estimate for the mean. Let's return to the wrench factory.

You own a wrench factory and want to measure the average length of the wrenches to 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 jackknife estimation to get the average lengths.

Examine the variable `wrench_lengths`

in the shell.

Instructions

**100 XP**

- Get a jackknife sample by iteratively leaving one observation out of
`wrench_lengths`

and assigning it to`jk_sample`

. - Calculate the mean of
`jk_sample`

and append it to`mean_lengths`

. - Finally, calculate the jackknife estimate
`mean_lengths_jk`

as the mean of the`mean_lengths`

array.