2nd Edition

ISBN: 9781259724275

Author: William Navidi, Barry Monk

Publisher: McGraw-Hill Education

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Textbook Question

Chapter 1.3, Problem 30E

Another Salk Vaccine Trial: Another study of the Salk vaccine, conducted at the same time as the trial described in Exercise 29, used a different design. In this study, approximately 350,000 second graders were invited to participate. About 225,000 did so, and the other 125,000 refused. All of the participating second graders received the vaccine. The control group consisted of approximately 725,000 first and third graders.

They were not given any placebo, so no consent was necessary.

Was this a randomized experiment?
Was it double-blind?
The treatment group consisted of children who had consent to participate. The control group consisted of all first and third graders. It turned out that the results of this study seriously underestimated the effectiveness of the vaccine. Use the information provided in Exercise 29(c) to explain why.

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Chapter 1.3, Problem 29E

Chapter 1.4, Problem 3E

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state whether the investigation in question is an observational study or a designed experiment. Justify your answer in each case. The Salk Vaccine. In the 1940s and early 1950s, the public was greatly concerned about polio. In an attempt to prevent this disease, Jonas Salk of the University of Pittsburgh developed a polio vaccine. In a test of the vaccine’s efficacy, involving nearly 2 million grade-school children, half of the children received the Salk vaccine; the other half received a placebo, in this case an injection of salt dissolved in water. Neither the children nor the doctors performing the diagnoses knew which children belonged to which group, but an evaluation center did. The center found that the incidence of polio was far less among the children inoculated with the Salk vaccine. From that information, the researchers concluded that the vaccine would be effective in preventing polio for all U.S. school children; consequently, it was made available for general use.

A psychologist has developed a mental alertness test. She wishes to study the effects (if any) of type of food consumed on mental alertness. Twenty-one volunteers were randomly divided into two groups. Both groups were told to eat the amount they usually eat for lunch at noon. At 2:00 P.M., all subjects were given the alertness test. Group A had a low-fat lunch with no red meat, lots of vegetables, carbohydrates, and fiber. Group B had a high-fat lunch with red meat, vegetable oils, and low fiber. The only drink for both groups was water. The test scores are shown below. Group A 75 82 96 54 78 59 67 53 97 85 66 Group B 70 80 79 60 62 71 52 69 64 88 51 74 Use a 10% level of significance to test the claim that there is no difference in mental alertness distributions based on type of lunch. (a) What is the level of significance?State the null and alternate hypotheses. Ho: Distributions are different. H1: Distributions are the same.Ho: Distributions are the same. H1:…

A psychologist has developed a mental alertness test. She wishes to study the effects (if any) of type of food consumed on mental alertness. Twenty-one volunteers were randomly divided into two groups. Both groups were told to eat the amount they usually eat for lunch at noon. At 2:00 P.M., all subjects were given the alertness test. Group A had a low-fat lunch with no red meat, lots of vegetables, carbohydrates, and fiber. Group B had a high-fat lunch with red meat, vegetable oils, and low fiber. The only drink for both groups was water. The test scores are shown below. Group A 77 93 75 52 72 79 83 46 89 53 65 Group B 57 82 84 85 64 92 86 59 43 68 50 67 Use a 10% level of significance to test the claim that there is no difference in mental alertness distributions based on type of lunch. (a) What is the level of significance? (b) Compute the sample test statistic. (Use 2 decimal places.) (c) Find the P-value of the sample test statistic. (Use 4 decimal places.)

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Solution Summary: The author explains the difference between randomized experiment and observational study.

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