How would you use a completely randomized experiment in each of the following se

Question

How would you use a completely randomized experiment in each of the following settings? Is a placebo being used or not? Be specific and give details. (a) A veterinarian wants to test a strain of antibiotic on calves to determine their resistance to common infection. In a pasture are 22 newborn calves. There is enough vaccine for 10 calves. However, blood tests to determine resistance to infection can be done on all calves. (Select all that apply.) No placebo is being used. After inoculation, test 10 calves to see if there is a difference in resistance to infection between the two groups. Use random selection to pick 5 calves to inoculate. After inoculation, test 5 calves to see if there is a difference in resistance to infection between the two groups. Use random selection to pick 10 calves to inoculate. After inoculation, test all calves to see if there is a difference in resistance to infection between the two groups. A placebo is used for the remaining 12 calves. (b) The Denver Police Department wants to improve its image with teenagers. A uniformed officer is sent to a school one day a week for 10 weeks. Each day the officer visits with students, eats lunch with students, attends pep rallies, and so on. There are 18 schools, but the police department can visit only half of these schools this semester. A survey regarding how teenagers view police is sent to all 18 schools at the end of the semester. (Select all that apply.) No placebo is being used. Use random selection to pick 18 schools to visit. A placebo is used for the remaining 9 schools. After the police visits, survey 9 of the schools to see if there is a difference in views between the two groups. Use random selection to pick nine schools to visit. After the police visits, survey all the schools to see if there is a difference in views between the two groups. (c) A skin patch contains a new drug to help people quit smoking. A group of 75 cigarette smokers have volunteered as subjects to test the new skin patch. For one month, 40 of the volunteers receive skin patches with the new drug. The other volunteers receive skin patches with no drugs. At the end of the two months, each subject is surveyed regarding his or her current smoking habits. (Select all that apply.) Use random selection to pick 35 volunteers for the skin patch with the drug. Use random selection to pick 40 volunteers for the skin patch with the drug. No placebo is being used. Then record the smoking habits of the 40 volunteers to see if a difference exists between the two groups. A placebo patch is used for the remaining 35 volunteers in the second group. Then record the smoking habits of all volunteers to see if a difference exists between the two groups. Then record the smoking habits of the 35 volunteers to see if a difference exists between the two groups.

Explanation / Answer

(a) Use a random selection to pick 10 calves to inoculate;. We should test all calves;

No placebo is being used as other 12 calves did not get anything.

There is no placebo being used, as a “fake” vaccine is not administered to the control group calves.

Note :-

The placebo effect occurs when a subject receives no treatment but (incorrectly) believes he or she is in fact receiving treatment and responds favorably.

(b)

Use random selection to pick 9 schools to visit. Then survey all the schools to see if there is a difference in views between the two groups. There is no placebo being used.

No placebo is being used.

Use random selection to pick nine schools to visit.

After the police visits, survey all the schools to see if there is a difference in views between the two groups.

(c)

Use random selection to pick 40 volunteers for the skin patch with the drug.

A placebo patch is used for the remaining 35 volunteers in the second group. (The remaining volunteers don't know that they have patch with no drug)

Then record the smoking habits of all volunteers to see if a difference exists between the two groups.

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