Question: Bootstrap percentile confidence interval for average repair time. Consider the small random subset of the Verizon data in Exercise. Bootstrap the sample mean using 1000 resamples.

(a) Make a histogram and Normal quantile plot. Does the bootstrap distribution appear close to Normal? Is the bias small relative to the observed sample mean?

(b) Find the 95% bootstrap t confidence interval.

(c) Give the 95% bootstrap percentile confidence interval and compare it with the interval in part (b).

Exercise: A small bootstrap example. To illustrate the bootstrap procedure, let's bootstrap a small random subset of the Verizon data:

26.47      0.00      5.32      17.30       29.78       3.67

(a) Sample with replacement from this initial SRS by rolling a die. Rolling a 1 means select the first member of the SRS, a 2 means select the second member, and so on. (You can also use Table B of random digits, responding only to digits 1 to 6.) Create 20 resamples of size n = 6.

(b) Calculate the sample mean for each of the resamples.

(c) Make a stemplot of the means of the 20 resamples. This is the bootstrap distribution.

(d) Calculate the bootstrap standard error.