Webassign Section 1.3
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) B) The Denver Police Department wants to improve its image with teenagers. A uniformed officer is sent to a school 1 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 the apply) 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)
A) After inoculation, test all 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. No placebo is being used. B) 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. No placebo is being used. C) Then record the smoking habits of all 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.
The New York Times did a special report on polling that was carried in papers across the nation. The article pointed out how readily the results of survey can be manipulated. Some features that can influence the results of a poll include the following: the number of possible responses, the phrasing of the question, the sampling techniques used (voluntary response or sample designed to be representative), the fact that words may mean different things to different people, the questions that precede the question of interest, and finally, the fact that respondents can offer opinions on issues they know nothing about. A) Consider the expression "over the last few years." Do you think that this expression means the same time span to everyone? What would be a more precise phrase? B) Consider this question: "Do you think fines for running stop signs should be doubled?" Do you think the response would be different if the question "Have you ever run a stop sign?" preceded the question about fines? C) Consider this question: "Do you watch too much television?" What do you think the responses would be if the only responses possible were yes or no? D) What do you think the responses would be if the possible responses were rarely, sometimes, or frequently?
A) No, it could mean 2 years, 3 years, 7 years, etc. "Over the past 5 years" B) The responses would be more negative towards fines being doubled because the people who have ran a stop sign would not want to pay double. C) I think the responses would more "no" because people do not have many options to pick. D) I think the responses would be more "rarely" because some people might not want to admit they watch too much television.
Zane is examining two studies involving how different generations classify specified items as either luxuries or necessities. In the first study, generation A is defined to be people ages 12-23. The second study defined generation A to be people ages 16-27. Zane notices that the first study was conducted in 2004 while the second one was conducted in 2008. A) Are the two studies inconsistent in their description of generation A? B) According to the 204 study, what are the birth years of generation A?
A) No, the age ranges updated with the studies. B) 1981-1992
Which technique for gathering data (sampling, experiment, simulation, or census) do you think was used in the following studies? A) An analysis of a sample of 31,000 patients from New York hospitals suggests that the poor and the elderly sue for malpractice at one-fifth the rate of wealthier patients (Journal of the American Medical Association). B) The effects of wind shear on airplanes during both landing and takeoff were studied by using complex computer programs that mimic actual flight. C) A study of all league football scores attained through touchdowns and field goals was conducted by the National Football League to determine whether field goals account for more scoring events than touchdowns (USA Today). D) An Australian study included 588 men and women who already had some precancerous skin lesions. Half got skin cream containing a sunscreen with a sun protection factor of 17; half got an inactive cream. After 7 months, those using the sunscreen with the sun protection had fewer precancerous skin lesions (New England Journal of Medicine)
A) Sampling B) Simulation C) Census D) Experiment
Which technique for gathering data (observational study or experiment) do you think was used in the following studies? A) The Colorado Division of Wildlife netted and released 774 fish at Quincy Reservoir. There were 219 perch, 315 blue gill, 83 pike, and 157 rainbow trout. B) The Colorado Division of Wildlife caught 41 bighorn sheep on Mt. Evans and gave each one an injection to prevent heart worm. A year later, 38 of these sheep did not have heart worm, while the other three did. C) The Colorado Division of Wildlife imposed special fishing regulation on the Deckers section of the South Platte River. All trout under 15 inches had to be released. A study of trout before and after the regulation went into effect showed that the average length of a trout increased by 4.2 inches after the new regulation. D) An ecology class used binoculars to watch 23 turtles a Lowell Ponds. It was found that 18 were box turtles and 5 were snapping turtles.
A) This is an observational study because observations and measurements of individuals are conducted in a way that doesn't change the response or the variable being measured. B) This is an experiment because a treatment was deliberately imposed on the individuals in order to observe a possible change in the response or variable being measured. C) This is an experiment because a treatment was deliberately imposed on the individuals in order to observe a possible change int he response or variable begin measured. D) This is an observational study because observations and measurements of individuals are conducted in a way that doesn't change the response of the variable being measured.
An agricultural study is comparing the harvest volume of two types of barley. The site for the experiment is bordered by a river. The field is divided into eight plots of approximately the same size. The experiment calls for the plots to be blocked into four plots per block. Then, two plots of each block will be randomly assigned to one of the two barley types. Two blocking schemes are shown below, with one block indicated by the white region and the other by the grey region. Which blocking scheme, A or B, would be best? Explain.
Based on the information, Scheme A will be better because the block bordering the river is different from the block away from the river.
Consider a completely randomized experiment in which a control group is given a placebo for congestion relief and a treatment group is given a new drug for congestion relief. Describe a double-blind procedure for this experiment.
Neither the patients nor those administering the treatments know which patients received which treatments.
What are some benefits of such a procedure? (select all that apply)
This process should eliminate potential bias from patient psychology regarding benefits of the drug. This process should eliminate potential bias from the treatment administrators
