1. How would you use a completely randomized experiment in each of the following
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Question
1. 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.)
-Use random selection to pick 5 calves to inoculate.
-No placebo is being used.
-After inoculation, test 5 calves to see if there is a difference in resistance to infection between the two groups.
-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 10 calves to inoculate.
-A placebo is used for the remaining 12 calves.
-After inoculation, test all calves to see if there is a difference in resistance to infection between the two groups.
(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.)
-After the police visits, survey all the schools to see if there is a difference in views between the two groups.
-After the police visits, survey 9 of the schools to see if there is a difference in views between the two groups.
-No placebo is being used.
-A placebo is used for the remaining 9 schools.
-Use random selection to pick nine schools to visit.
-Use random selection to pick 18 schools to visit.
(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.)
-Then record the smoking habits of the 35 volunteers to see if a difference exists between the two groups.
-No placebo is being used.
-Use random selection to pick 35 volunteers for the skin patch with the drug.
-Then record the smoking habits of the 40 volunteers to see if a difference exists between the two groups.
-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.
-Then record the smoking habits of all volunteers to see if a difference exists between the two groups.
2. a)A radio talk show host asked listeners to respond either yes or no to the question, "Is the candidate who spends the most on a campaign the most likely to win?" Fifteen people called in and nine said yes. What is the implied population?
-all radio listeners
-all adults
-all listeners of the radio talk show
-all callers
b)What is the variable?
-number of listeners
-opinion of a listener
-opinion of a caller
-number of callers
c) Can you detect any bias in the selection of the sample?
-No, there is no bias in the selection of this sample.
-Yes, voluntary response. Those with the strongest opinions are most likely to call in.
-Yes, nonresponse. Many listeners may not call in.
-Yes, there is a systematic bias against those that are not listening to the talk show.
3. One cable station knows that approximately 30% of its viewers have TIVO and can easily skip over advertising breaks. You are to design a simulation of how a random sample of seven station viewers would respond to the question, "Do you have TIVO?" How would you assign the random digits 0 through 9 to the responses "Yes" and "No" to the TIVO question? (Hint: Use your random digit assignment and the random-number table to generate the responses from a random sample of seven station viewers.)
-Assign digits so that 5 out of the 10 digits correspond to the answer "Yes" and 5 of the digits correspond to the answer "No."
-Assign even digits to correspond to the answer "Yes" and assign odd digits to correspond to the answer "No."
-Assign digits so that 7 out of the 10 digits correspond to the answer "Yes" and 3 of the digits correspond to the answer "No."
-Assign digits so that 3 out of the 10 digits correspond to the answer "Yes" and 7 of the digits correspond to the answer "No."
4. A die is a cube with dots on each face. The faces have 1, 2, 3, 4, 5, or 6 dots. The table below is a computer simulation (from the software package Minitab) of the results of rolling a fair die 20 times.
(a) Assume that each number in the table corresponds to the number of dots on the upward face of the die. Is it appropriate that the same number appears more than once? Why?
-No, the outcome of the die roll cannot repeat.
-Yes, each distinct number of dots can appear on more than one face of the die.
-No, each distinct number of dots cannot appear on more than one face of the die.
-Yes, the outcome of the die roll can repeat.
b) What is the outcome of the sixth roll?
DATA DISPLAY ROW C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 1 5 2 2 2 5 3 2 3 1 4 2 3 2 4 5 4 5 3 5 3 4Explanation / Answer
Question 1
Part A:
(Answer) No placebo is being used: No fake vaccine is administered to calves, hence placebo is not being used.
(Answer) 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 10 calves to inoculate.: Randomization can be done by numbering all calves from 1 to 22 anf then randomly generate 10 numbers. Now, select the calves corresponding to these numbers.
Part B:
(Answer) After the police visits, survey all the schools to see if there is a difference in views between the two groups. Surveying of representative samples from each school according to the categories - where police officer visited and where police office didn't visit, will reveal if there is any difference of image of Police created in minds of students.
(Answer) No placebo is being used. No fake police officer has visited the schools. Hence, no placebo effect is being used.
(Answer) Use random selection to pick nine schools to visit. Random selection of nine school will ensure no bias is created while selecting the school and hence results will be least affected.
Part C:
(Answer) Use random selection to pick 40 volunteers for the skin patch with the drug.
(Answer) A placebo patch is used for the remaining 35 volunteers in the second group.
(Answer) Then record the smoking habits of all volunteers to see if a difference exists between the two groups.
Placebo effect is used on 35 volunteers whom skin patch without any drug is given. 40 students with random selection will remove any bias from experiment. Comparison of smoking habits between these two groups will give clear result on the real effects of drug.
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