Statistics Chapter 9 REVIEW

4. Eight subjects who suffer from chronic fatigue syndrome volunteer to take part in an experiment to see if shark fin extract will increase their energy level. Half of the volunteers are to be given shark fin extract twice a day and the other half a placebo twice a day. The names of the subjects are given below, and each name is given a numerical label. Use the following list of random digits to assign four subjects to the shark fin treatment. Read the table from left to right, and use the numerical labels given above to the names. 15917 50495 11384 44982 20751 27498 12069 45287 71753 90236 66419 84533 The people assigned to the shark fin treatment are

Adams, Lewis, Simpson, and Howard.

10. In an experiment on a new drug to determine the most effective dosage and method of administration, subjects were randomly assigned to either a 5, 10, 15, or 20 dosage of the active drug. In addition, the method of delivery of the drug (pill, skin patch, or nasal mist) was considered. In this experiment, there were how many treatments?

12

9. In an experiment on a new drug, subjects were randomly assigned to either a placebo or the active drug. In addition, the method of delivery of the drug (pill, skin patch, or nasal mist) was considered. In this experiment, there were how many factors?

2

5. One hundred volunteers who suffer from depression are available for a study involving a new drug that is thought to be effective in treating depression. The researchers want to compare the new drug to the drug currently in use. It is believed that men and women may respond differently to the drugs. Fifty of the volunteers are selected at random and are given the new drug, and the other fifty are given the drug currently in use. A psychiatrist evaluates the symptoms of all volunteers after four weeks in order to determine if there had been substantial improvement in the severity of the depression. Which of the following is correct?

This is an example of a completely randomized design.

3. In a recent study, a random sample of children in grades two through four showed a significant negative relationship between the amount of homework assigned and student attitudes. The amount of homework assigned is

an explanatory variable.

1. In order to determine if living next to high-voltage power lines increases your chance of getting cancer, researchers selected several homes at random, determined if they were within 50 yards of a high-voltage power line, and recorded if anyone in the home had cancer. They compared the proportion of cancer cases in homes within 50 yards of a high-voltage power line to the proportion in homes more than 50 yards from a high-voltage power line. This is

an observational study.

11. A researcher in early education believes that kindergarten-age children are more receptive to help from a female teacher than from a male teacher. From the list of kindergarten teachers in the state, the researcher randomly samples four classes in which the teachers are male and four in which the teachers are female. The students in each of these classes are interviewed and a measure of how receptive they are to help from the teacher is determined. This is an example of

an observational study.

8. In an experiment to determine if a new type of fertilizer is better than the current "standard" fertilizer for growing corn, twenty plots of land are randomly assigned one of the two types. At the end of the growing season, the corn yields for each plot are measured. It was found that plots which were located closer to a highway had smaller yields than other plots. The following year, the experiment was redone, but the plots were randomly assigned to either the new or old fertilizer according to the distance from the highway. The new experiment was

blocked.

6. In an experiment to determine if a new type of fertilizer is better than the current "standard" fertilizer for growing corn, twenty plots of land are randomly assigned one of the two types. At the end of the growing season, the corn yields for each plot are measured. It was found that plots which were located closer to a highway had smaller yields than other plots. In this experiment, distance from the highway is a

lurking variable.

7. In an experiment to determine whether Avon's Skin-So-Soft® is as good as Deep Woods Off® at repelling mosquitoes, a researcher recruited several students and randomly put Skin-So-Soft on one arm and Off on the other. The students then were instructed to wander the campus for several hours, not going inside a building. When they returned, the number of mosquito bites was counted on each arm. This is an example of a

matched pairs experiment.

2. For one kindergarten class in his district, a researcher determines which children already can read simple words and which children cannot upon entering kindergarten. The children are followed until third grade, at which point they are tested to determine the grade level at which they are reading. Those children who were reading simple words upon entering kindergarten are found to be reading at a higher level than those who could not read simple words upon entering kindergarten. Some educators are skeptical, as they argue that those students with higher innate reading abilities were probably those reading simple words upon entering kindergarten, thus it is not surprising that they are reading at a higher level in third grade. The response variable in this study is

the grade level at which they are reading in third grade.