AP Stats Final Exam

A nutritionist wants to study the effect of storage time (6, 12, and 18 months)on the amount of vitamin C present in freeze dried fruit when stored for these length of time. Vitamin C is measured in milligram per 100 milligrams of fruit. Six fruit packs were randomly assigned to each of the three storage times. The treatment, experimental unit, and response are respectively.

A specific storage time, a fruit pack, amount of vitamin C.

A researcher observes that, on average, the number of divorces in cities iwth Major League Baseball teams is larger than in cities without Major League teams. The most plausible explanation for this observed association is that the

Association is due to the presence of a lurking variable (Major League teams tend to be in large cities with more people, hence a greater number of divorces.)

an airline that wants to assess customer satisfaction chooses a Random Sample of 10 of its flights during a single month and asks them to fill out a survey. This is an example of

Cluster Sample

Control groups are used in experiments in order to

Control the effects of outside variables on the outcome.

The following numbers appear in a table of random digits: 38683 50279 38224 09844 13578 282511 12708 24684 A scientist willb e measuring the total amount of leaf litter in a random sample (n=5) of forest sites selected without replacement from a population of 45 sites. The sites are labeled 01, 02..., 45 and she starts at the beginning of the line of random digits and takes consecutive pairs of digits. Which of the following is correct?

Her sample is 38, 35, 02, 22, 40

a civil engineer is testing the reliability of traffic signal controllers produced by two different companies. he has 20 sets of controllers from each company, and he has been given clearance to install them at 40 different intersections in the city. The most important reason for Random Assignment is that

Randomization is a good way to create two groups of 20 intersections that are as similar as possible, so that comparisons can be made between the two groups

A researcher for a consumer products company is field testing a new formula for laundry detergent. He has contracted with 60 families each with two children, who have agreed to test the product. He randomly assigns 30 families to the group that will use the new formula important reason for this randomassignment is that

Randomization is a good way to create two groups of 30 families that are as similar as possible, so that comparisons can be made between the two groups.

which of the following statements is FALSE?

Sophisticated statistical methods can always correct the results if the population you are sampling from is different from the population of interest, for example due to undercoverage

A survey was done in the town of Mechanicsville to estimate the proportion of cars that are red and made by companies based in Japan.A random simple of 25 cars from a student parking lot at Lee-Davis High school was taken. Which of the following statements is not correct?

The results will be the same regardless of the time of day that the sample is taken.

80 volunteers who use an Over-The-Counter allergy medication have been recruited to participate in a trial of a new allergy medication. Volunteers are randomly assigned, each is asked after two weeks. which of the following best describes a conclusion that can be drawn from this study?

We can determine whether the new drug reduces symptoms more than the old drug for the subjects in the study

A survey is to be administered to recent graduates of a certain nursing school in order to compare the starting salaries of women and men. For a random simple of graduates, three variables are to be recorded: sex, starting salary, and area of specialization. Which of the follow best describes a conclusion that can be drawn from this study?

Whether there is an association between sex and starting salary among graduates of this nursing school.

you work for an advertising agency that is preparing a new television commercial to appeal to women. You have been asked to design an experiment to compare the effectiveness of three versions of the commercial. Each subject will be show one of the three versions and then asked her attitude toward the product. You think there may be large differences between women who are empaled outside the home and those who are not. Because of these differences, you should use:

a block design

to test the effects of a new fertilizer, 100 plots were divided in Half. fertilizer A is randomly applied to one half, and B to the other. that is

a block design, but not a matched pairs experiment

To test the effect of music on productivity, a group of assembly line workers are given portable mp3 players to play whatever music they choose while working for one month. For another month, they work without music. THe order of the two treatments for each worker is determined randomly This is

a matched pairs experiment

what electrical changes occur in muscles as they get tired? students hold their arms above their shoulders as long as they can.meanwhile, the electrical activity in their arm muscles is measured, this is

an uncontrolled experiment

A maple sugar manufacturer wants to estimate the average trunk diameter of sugar maples trees in a large forest. There are too many trees to list them all and take a SRS, so he divides the forest into several hundred 10 meter by 10 meter plots, selects 25 plots at random, and measures the diameter of every sugar maple in each one. This is an example of a

cluster sample

We wish to draw a sample of 5 without replacement from a population of 50 households. Suppose the households are number 01, 02,...50, and suppose that the relevant line of the random number table 11362 35692 90842 46843

households 11, 36, 23, 08, 42

an experiment to measure the effect of giving growth hormones to Girls affected by turners syndrome was carried out recently. all 34 gils in the study were given and measured a year later. which is not a problem?

nonresponse bias

A new headache remedy was given to a group of 25 subjects who had headaches. Four hours after taking the new remedy, 20 of the subjects reported that their headaches had disappeared. From this information you conclude.

nothing, because there is no control group for comparison

According to the 1990 census, those states with an average number of people X, who fail to complete high school tend to have an above average infant deaths, Y. the most plausible explanation for the POSITIVE association between dropouts and baby deaths is:

the association between X and Y is purely coincidental