Sickle-cell disease
1- Sickle-cell disease is a painful disorder of the red blood cells that in the United States affects mostly African-Americans. To investigate whether the drug hydroxyurea can reduce the pain associated with sickle-cell disease, a study by the National Institutes of Health gave the drug to 150 sickle-cell sufferers and a placebo to another 150. The researchers then counted the number of episodes of pain reported by each subject. What is the response variable in this study?
A) The drug hydroxyurea.
B) The number of episodes of pain.
C) The presence of sickle-cell disease.
D) The number of red blood cells.
2- One hundred volunteers who suffer from severe depression are available for a study. Fifty are selected at random and are given a new drug that is thought to be particularly effective in treating severe depression. The other 50 are given an existing drug for treating severe depression. A psychiatrist evaluates the symptoms of all volunteers after four weeks in order to determine if there has been substantial improvement in the severity of the depression.
Q: What is the explanatory variable or factor in this study?
Group of answer choices
A) Which drug do the volunteers receive.
B) The use of randomization and the fact that this was a comparative study.
C) The extent to which the depression was reduced.
D) The use of a psychiatrist to evaluate the severity of depression.
3- In order to assess the opinion of students at a large university about campus snow removal, a reporter for the student newspaper interviews the first 12 students he meets who are willing to express their opinions.
What set of students make up the sample?
- All those students favored prompt snow removal.
- All students at universities receive substantial snow.
- The 12 students were interviewed.
- All students at the University of Minnesota.
4- A public opinion poll in Ohio wants to determine whether registered voters in the state approve of a measure to ban smoking in all public areas. They select a simple random sample of 50 registered voters from each county in the state and ask whether they approve or disapprove of the measure.
Fill in the blank. The proportion of registered voters in the state who approve of banning smoking in public areas is an example of _________
A) a sample proportion.
B) a statistic.
C) a parameter.
D) an unbiased statistic.
5- Fill in the blank. A free cholesterol screening program is set up in the downtown area during the lunch hour. Individuals can walk in and have their cholesterol measured for free. One hundred seventy-three people use the service, and their average cholesterol is 217.8. The value 217.8 is an example of _________
- a sample proportion.
- a statistic.
- a parameter.
- an unbiased parameter.
6- A particularly common question in the study of wildlife behavior involves observing contests between “residents” of a particular area and “intruders.” In each contest, the “residents” either win or lose the encounter (assuming there are no ties). Observers might record several variables, some of which are listed below. Which of these variables is categorical?
- The duration of the contest (in seconds).
- The number of animals involved in the contest.
- Whether the “residents” win or lose.
- The total number of contests won by the “residents”.
