Problem 5 Identify which of these types of sampling (random, stratified, systematic, cluster, convenience) is used when a sample of the 637,133 stockholders of IBM is obtained as described. Then determine whether the sampling scheme is likely to result in a sample that is representative of the population of all 637,133 stockholders. i. A complete list of all stockholders is compiled and every 500th name is selected. ii. At the annual stockholders' meeting, a survey is conducted of all who attended. iii. Fifty different stockholders are randomly selected, and a survey is made of all their clients who own shares of IBM. iv. All of the stockholder zip codes are collected, and 5 stockholders are randomly selected from each zip code. b. Determine whether the given description corresponds to an observational study or a randomized experiment. i) Much controversy arose over a study of patients with syphilis who were not given a treatment that could have cured them. Their health was followed for years after they were found to have syphilis. ii) A medical researcher wants to determine whether exercising can lower blood pressure. She recruits 100 people with high blood pressure to participate in the study. She assigns a random sample of 50 of them to pursue an exercise program that includes daily swimming and jogging. She assigns the other 50 to refrain from vigorous activity. She measures the blood pressure of each of the 100 individuals both before and after the study