An inspector samples cans from a truckload of canned cream corn to estimate the average number of worm fragments per can. The truck contains 580 three-packs (three cans per package). The inspector samples 12 three-packs at random, opens all the cans, and finds the following number of worm fragments in each pack: Three-Pack Can 1 2 3 4 5 6 7 8 9 10 11 12 1140340537340 2521697503131 3742683125490 (a) Explain why this is a cluster sample and not a stratified sample. (b) Give the sampling unit (psu) and the observation unit (ssu). (c) Estimate the mean number of worm fragments per can and the standard error of your estimate. Provide a 95% confidence interval. (d) Based on this sample the intracluster correlation (ICC) is estimated to be 0.42. Use the ICC to estimate the design effect. Was the cluster sample more or less efficient than an SRS