Exam
Name___________________________________

SHORT ANSWER.  Write the word or phrase that best completes each statement or answers the question.
An article in a local newspaper reported that dogs kept as pets tend to be overweight. Veterinarians say that diet and exercise will help these chubby dogs get in shape. The veterinarians propose two different diets (Diet A and Diet B) and two different exercise programs (Plan 1 and Plan 2). Diet A owners control the portions of dog food and dog treats; Diet B a mixture of fresh vegetables with the dog food and substitute regular dog treats with baby carrots.  three 30-minute walks a week; Plan 2 20-minute walks daily. Sixty dog owners volunteer to take part in an experiment to help their chubby dogs lose weight.
1) Identify the following
a. the subjects
b. the factor(s) and the number of level(s) for each
c. the number of treatments
d. whether or not the experiment is blind (or double-blind)
e. the response variable	1)  _____________

2) Design an experiment to determine whether the diet and exercise programs are effective in helping dogs to lose weight.	2)  _____________

A group of people are concerned that the coach of a local high school men's and women's basketball teams alters the amount of air in the basketball to gain an unfair advantage over opponents during home games. The idea is that the basketballs are pumped up with one pound per square inch less air than required, and his teams practiced with these altered balls all week prior to home basketball games. Since these under-pumped basketballs would react differently to being shot at a basket, the team that practiced with these balls would have an unfair advantage when it came to shooting free throws.
3) Describe how to use a retrospective study to determine if the home teams have an unfair advantage when shooting free-throws.	3)  _____________

4) Describe how to use a prospective study to determine if the home teams have an unfair advantage when shooting free-throws.	4)  _____________

5) Design an experiment to determine if the home teams have an unfair advantage when shooting free-throws.	5)  _____________

Researchers plan to investigate a new medication that may reduce blood pressure for individuals with higher than average blood pressure. 90 volunteers with higher than average blood pressure are solicited. Volunteers are randomly assign 100 mg of the medicine, 200 mg of the medicine, or a placebo. Blood pressure will be measured at the beginning and at the conclusion of the study.
6) Identify the subjects.	6)  _____________

7) Identify the treatments.	7)  _____________

8) Identify the response variable.	8)  _____________

9) Describe an advantage to random assignment of treatment.	9)  _____________

10) Describe an advantage of the placebo.	10)  _____________

11) Describe a disadvantage of using volunteers in this study.	11)  _____________

12) Is this study blind?	12)  _____________

Max wants to start a farm to grow mussels. He needs to determine the best environment for growing them. He is going to try two different amounts of salt in the water (salinity) and three different water temperatures. For his experiment he has 18 aquariums, each with 20 mussels. He wants to see which environment produces the largest mussels.
13) Identify the subjects.	13)  _____________

14) Identify the factors and levels.	14)  _____________

15) Identify the treatments.	15)  _____________

16) Identify the response variable.	16)  _____________

17) Describe an advantage to random assignment of treatment.	17)  _____________

18) Explain how replication would be used in this study.	18)  _____________

19) Someone suggested that Max arrange the tanks so that six with the lowest temperature are on one end of the room, and the six with the highest temperature are at the other end of the room. Explain how this could introduce confounding into the experiment.	19)  _____________

20) Would it make sense to have a control group that did not get any of the treatments described above?	20)  _____________

1) a.  60 chubby dogs
b.  diet (two levels) and exercise (two levels)
c.  four treatments (Diet A and Plan 1, Diet A and Plan 2, Diet B and Plan 1, Diet B and Plan 2)
d.  This design is at best single-blind, since the owners know which diet and exercise plan their 
dogs are on, but the evaluators do not have to be given this information.
e.  weight loss
2) 

3) A retrospective study is an observational study in which past games are reviewed to see how many free-throws the team made when they had the altered basketballs versus when they had basketballs pumped up correctly. The differences in the number or percentage of free-throws made would be compared between the two types of basketballs.
4) A prospective study is an observational study in which teams are selected and then their future free-throws are recorded to see if they improve when they have the altered basketballs. The differences in the number or percentage of free-throws made would be compared between the two types of basketballs.
5) Subjects being studied basketball games
Treatment Factor in the experiment air pressure in the basketball
Levels of factor standard basketball air pressure and one pound less than standard basketball air
pressure
Response variable number (or percentage) of free-throws for the team that practiced with the under-inflated basketballs
Design Home team will practice all week with under-inflated basketballs. Games will be played with under-inflated basketballs or regulation basketballs, determined at random at game time. We'll record the team's free-throw performance. Results will be compared for games using the under-inflated basketballs to games played with properly inflated basketballs.
Double-blind experiment The type of basketball used for each game will be determined by a person handling the basketballs, without letting the players or the coach know which ball is being used. Basketballs will look identical.
Nature and scope of conclusion the number or percentage of free-throws made by each team will be evaluated to determine if there is an improvement in rebounding when using the under-inflated basketballs. If there is a difference with the altered basketballs, practicing during the week with the under-inflated basketballs would give the home team an unfair advantage over the visiting team who has not practiced with the under-inflated basketballs.
6) The subjects are the 90 volunteers with higher than average blood pressure.
7) There are 3 treatments, 100 mg, 200 mg, and the placebo.
8) The response variable is the change in blood pressure.
9) Randomization will equalize variability for which we cannot control, helping to ensure comparable, homogeneous treatment groups. We may be able to establish causation as opposed to association.
10) We have an extra comparison with a control group. Blood pressure may change due to other
variables.
11) We are not able to generalize the results to a larger population.
12) The subjects are blind, assuming the 100 mg, 200 mg and placebo appear to be the same.
13) The subjects are the 18 tanks of mussels.
14) There are two factors temperature and salinity. There are three levels of temperature and two levels of salinity.
15) There are six treatments High salinity with high temperature, high salinity with medium temperature, high salinity with low temperature, low salinity with high temperature, low salinity with medium temperature, low salinity with low temperature,
16) The size of the mussels.
17) It would reduce the effect of confounding variables.
18) Since there are six treatments, each could be assigned to 3 tanks.
19) There could be something about the location in the room that affects the growth of the mussels. If this is the case, Max wouldn’t be able to tell whether location in the room or the treatment was responsible for the observed growth.
20) No. If you used no salt, the mussels would die. And it makes no sense to have no temperature.