Deck 3: Gathering Data

Question 1

In order to see which variety of apple tree produces more fruit, a farmer sets up an experiment. He
Has three plots of land with different soil and natural water availability. Each plot has room for
Eight trees. The farmer randomly selects four locations in each plot for the first variety of tree and
The other four get the second variety. This experiment is…

A) completely randomized with two factors
B) completely randomized with one factor: the variety of tree
C) randomized block, blocked by plot of land
D) completely randomized with one factor: the plot of land
E) randomized block, blocked by variety of tree

Answer 1

C

Question 2

Which is important in designing a good experiment?
I) Randomization in assigning subjects to treatments.
II) Control of potentially confounding variables.
III) Replication of the experiment on a sufficient number of subjects.

A) I and III
B) I, II, and III
C) I and II
D) I only
E) II and III

Answer 2

B

Question 3

Which of these is not an advantage of using a stratified sample instead of a simple random sample?

A) the stratified sample eliminates the need for randomization
B) the stratified sample reduces bias
C) the stratified sample allows you to get more reliable estimates using the same sample size
D) the stratified random sample allows you to get information about each stratum
E) the stratified sample reduces sample to sample variability

Answer 3

B

Question 4

A researcher wants to compare the effect of a new type of shampoo on hair condition. The
Researcher believes that men and women may react to the shampoo differently. Additionally, the
Researcher believes that the shampoo will react differently on hair that is dyed. The subjects are
Split into four groups: men who dye their hair; men who do not dye their hair; women who dye
Their hair; women who do not dye their hair. Subjects in each group are randomly assigned to the
New shampoo and the old shampoo. This experiment

A) has two factors (gender and whether hair is dyed) blocked by shampoo type.
B) has three factors (shampoo type, gender, whether hair is dyed).
C) has two factors (shampoo type and whether hair is dyed) blocked by gender
D) has one factor (shampoo type), blocked by gender and whether hair is dyed.
E) is completely randomized.

Question 5

Double-blinding in experiments is important so that
I) The evaluators do not know which treatment group the participants are in.
II) The participants do not know which treatment group they are in.
III) No one knows which treatment any of the participants is getting.

A) II only
B) I and II
C) III only
D) I, II, and III
E) I only

Question 6

Which of the following is not required in an experimental design?

A) All of these are required in an experimental design.
B) replication
C) randomization
D) control
E) blocking

Question 7

A factory has 20 assembly lines producing a popular toy. To inspect a representative sample of 100
Toys, quality control staff randomly selected 5 toys from each line's output. Was this a simple
Random sample?

A) Yes, because each toy produced had an equal chance to be selected.
B) No, because toys do not come off the assembly line at random.
C) Yes, because a stratified sample is a type of simple random sample.
D) No, because not all combinations of 100 toys could have been chosen.
E) Yes, because the toys were selected at random.

Question 8

A company has tried to improve the effectiveness of its dishwashing detergent and wants to see if it
Works better than the original formula. They use 6 identical new dishwashers and load them
Identically with dirty dishes. Three packs of each of the two types of detergent are used, and they
Are randomly assigned to one of the six dishwashers. After the load is run, they rate each load for
Overall cleanliness. Which of the following is true?

A) Because each brand is used in three dishwashers, replication is used properly.
B) The response variable is the type of detergent.
C) The explanatory variable is the different dishwashers.
D) Blinding is impossible in this experiment because they must be able to see the dishes.
E) A control group with no detergent at all is needed.

Question 9

Suppose the state decides to randomly test high school wrestlers for steroid use. There are 16 teams
In the league, and each team has 20 wrestlers. State investigators plan to test 32 of these athletes by
Randomly choosing two wrestlers from each team. Is this a simple random sample?

A) No, because not all possible groups of 32 wrestlers could have been the sample.
B) Yes, because the wrestlers were chosen at random.
C) Yes, because each wrestler is equally likely to be chosen.
D) Yes, because stratified samples are a type of simple random sample.
E) No, because a random sample of teams was not first chosen.

Question 10

It was discovered that a larger proportion of children who slept with nightlights later developed
Nearsightedness, compared to children who did not sleep with nightlights. The headlines read,
"Leaving a light on for you children causes nearsightedness!" Later it was pointed out that
Nearsighted people have more trouble seeing in the dark and are more likely to leave lights on at
Night for their kids. And those same nearsighted parents are likely to have nearsighted kids. This is
An example of

A) bias.
B) a placebo.
C) a lurking variable.
D) a randomized block design.
E) a control group.

Question 11

Which is true about sampling?
I) An attempt to take a census will always result in less bias than sampling.
II) Sampling error is usually reduced when the sample size is larger.
III) Sampling error is the result of random variations and is always present.

A) III only
B) I, II, and III
C) II only
D) I only
E) II and III

Question 12

A company sponsoring a new Internet search engine wants to collect data on the ease of using it.
Which is the best way to collect the data?

A) simulation
B) experiment
C) observational study
D) census
E) sample survey

Question 13

A chemistry professor who teaches a large lecture class surveys his students who attend his class
About how he can make the class more interesting, hoping he can get more students to attend. This
Survey method suffers from

A) response bias
B) voluntary response bias
C) nonresponse bias
D) undercoverage
E) none of these

Question 14

We wish to compare the average ages of the math and science teachers at your high school. Which
Is the best way to collect the data?

A) sample survey
B) observational study
C) census
D) experiment
E) simulation

Question 15

The principal of a small elementary school wants to select a simple random sample of 24 students.
The school has 12 classrooms with 18 students in each class. She decides to randomly select two
Students from each classroom. Is this a simple random sample?

A) No, because not all combinations of 24 students could have been chosen.
B) Yes, because the students were selected at random.
C) No, because each student did not have an equal chance of being selected.
D) Yes, because a stratified sample is a type of simple random sample.
E) Yes, because each student had an equal chance to be selected.

Question 16

If we wish to compare the average PSAT scores of boys and girls taking AP* Statistics at a high
School, which would be the best way to gather these data?

A) stratified sample
B) census
C) experiment
D) SRS
E) observational study

Question 17

In an experiment the primary purpose of blinding is to reduce …

A) bias.
B) randomness.
C) confounding.
D) variation.
E) undercoverage.

Question 18

Does Procellera Antimicrobial Wound Dressing help injuries heal faster? Researchers checked
Records of 38 patients who had been treated for acute or chronic wounds between 2010 and 2012.
They found that those who had been treated with Procellera
Healed almost twice as fast. This is a

A) retrospective study
B) randomized experiment
C) prospective study
D) survey
E) matched experiment

Question 19

In an experiment the primary purpose of blocking is to reduce

A) randomness.
B) variation.
C) confounding.
D) undercoverage.
E) bias.

Question 20

A researcher wants to compare the performance of three types of pain relievers in volunteers
Suffering from arthritis. Because people of different ages may suffer arthritis of varying degrees of
Severity, the subjects are split into two groups: under 60 and over 60. Subjects in each group are
Randomly assigned to take one of the medications. Twenty minutes later they rate their levels of
Pain. This experiment …

A) has two factors, medication and age.
B) has one factor (medication) blocked by age.
C) has one factor (age) blocked by medication type.
D) uses matched pairs.
E) is completely randomized.

Question 21

More dogs are being diagnosed with thyroid problems than have been diagnosed in the past. A
Researcher identified 50 puppies without thyroid problems and kept records of their diets for
Several years to see if any developed thyroid problems. This is a(n)

A) survey
B) retrospective study
C) prospective study
D) blocked experiment
E) randomized experiment

Question 22

The January 2005 Gallup Youth Survey telephoned a random sample of 1,028 U.S. teens and asked
These teens to name their favorite movie from 2004. Napoleon Dynamite had the highest percentage
With 8% of teens ranking it as their favorite movie. Which is true?
I) The population of interest is all U.S. teens.
II) 8% is a statistic and not the actual percentage of all U.S. teens who would rank this movie as
Their favorite.
III) This sampling design should provide a reasonably accurate estimate of the actual percentage of
All U.S. teens who would rank this movie as their favorite.

A) I only
B) I and II
C) II only
D) III only
E) I, II, and III

Question 23

A Columbia University study linked soda consumption to behavior problems in children.
Researchers examined data from a previous study that followed 2929 mother-child pairs. One
Survey asked about behaviors of the child and also about soda consumption. They found that the
More soda the kids drank, the more behavior problems they had. What aspect of a well-designed
Experiment is absent from this study?

A) blinding
B) randomization
C) all of these
D) a placebo
E) a control group

Question 24

Twenty dogs and 20 cats were subjects in an experiment to test the effectiveness of a new flea
Control chemical. Ten of the dogs were randomly assigned to an experimental group that wore a
Collar containing the chemical, while the others wore a similar collar without the chemical. The
Same was done with the cats. After 30 days veterinarians were asked to inspect the animals for fleas
And evidence of flea bites. This experiment is…

A) randomized block, blocked by type of collar
B) randomized block, blocked by species
C) completely randomized with one factor: the type of collar
D) completely randomized with one factor: the species of animal
E) completely randomized with two factors

Question 25

In an experiment the primary purpose of blocking is to

A) reduce the within-treatment variation.
B) eliminate the need for random assignment of treatments.
C) reduce the between-treatment variation.
D) eliminate confounding variables.
E) reduce bias.

Question 26

A school district administrator sent a survey to all teachers in the district. Only 30% of the teachers
Responded to the survey. Which of the following is true?
I) The people that did not responded are likely to be similar to those that did so he should use them
As the sample.
II) This survey design suffered from non-response bias.
III) Because he sent the survey to everyone, this is a census and the results can be applied to the
Whole population.

A) I and II only
B) I only
C) I, II, and III
D) II only
E) II and III only

Question 27

A researcher identified 100 men over forty who were not exercising and another 100 men over forty
With similar medical histories who were exercising regularly. She followed all the men for several
Years to see if there was any difference between the two groups in the rate of heart attacks. This is a
…

A) randomized experiment
B) matched pairs experiment
C) retrospective study
D) prospective study
E) survey

Question 28

Hoping to get information that would allow them to negotiate new rates with their advertisers,
Natural Health magazine phoned a random sample of 600 subscribers. 64% of those polled said they
Use nutritional supplements. Which is true?
I) The population of interest is the people who read this magazine.
II) "64%" is not a statistic; it's the parameter of interest.
III) This sampling design should provide the company with a reasonably accurate estimate of the
Percentage of all subscribers who use supplements.

A) I, II, and III
B) I only
C) I and III only
D) II and III only
E) I and II only

Question 29

Placebos are a tool for

A) randomization
B) sampling
C) control
D) blocking
E) blinding

Question 30

Suppose a school district decides to randomly test high school students for attention deficit
Disorder (ADD). There are three high schools in the district, each with grades 9-12. The school
Board pools all of the students together and randomly samples 250 students. Is this a simple
Random sample?

A) Yes, because the students were chosen at random.
B) No, because we can't guarantee that students from each school in the sample.
C) Yes, because each student is equally likely to be chosen.
D) No, because we can't guarantee that students from each grade in the sample.
E) Yes, because they could have chosen any 250 students from the district.

Question 31

The owner of a car dealership planned to develop strategies to increase sales. He hoped to learn the
Reasons why many people who visit his car lot do not eventually buy a car from him. For one
Month he asked his sales staff to keep a list of the names and addresses of everyone who came in to
Test drive a car. At the end of the month he sent surveys to the people who did not buy the car,
Asking them why. About one third of them returned the survey, with 44% of those indicating that
They found a lower price elsewhere. Which is true?
I) The population of interest is all potential car buyers.
II) This survey design suffered from non-response bias.
III) Because it comes from a sample 44% is a parameter, not a statistic.

A) II only
B) I and II
C) I only
D) II and III
E) I, II, and III

Question 32

Which is not a critical part of designing a good experiment?

A) All of these are important.
B) Replication of the on a sufficient number of subjects.
C) Random assignment of subjects to treatments.
D) Random selection of subjects.
E) Control of known sources of variability.

Question 33

Does regular exercise decrease the risk of cancer? A researcher finds 200 women over 50 who
Exercise regularly, pairs each with a woman who has a similar medical history but does not
Exercise, then follows subjects for 10 years to see which group develops more cancer. This is a

A) retrospective study
B) survey
C) matched experiment
D) randomized experiment
E) prospective study

Question 34

Which statement about bias is true?
I) Bias results from random variation and will always be present.
II) Bias results from a sampling method likely to produce samples that do not represent the
Population.
III) Bias is usually reduced when sample size is larger.

A) II only
B) I and III only
C) II and III only
D) I only
E) III only

Question 35

To check the effect of cold temperatures on the battery's ability to start a car researchers purchased
A battery from Sears and one from NAPA. They disabled a car so it would not start, put the car in a
Warm garage, and installed the Sears battery. They tried to start the car repeatedly, keeping track of
The total time that elapsed before the battery could no longer turn the engine over. Then they
Moved the car outdoors where the temperature was below zero. After the car had chilled there for
Several hours the researchers installed the NAPA battery and repeated the test. Is this a good
Experimental design?

A) No, because they should have tested other brands of batteries, too.
B) Yes
C) No, because they should have tested more temperatures.
D) No, because temperature is confounded by brand.
E) No, because the car and the batteries were not chosen at random.

Question 36

Which is true about randomized experiments?
I) Randomization reduces the effects of confounding variables.
II) Random assignment of treatments allows results to be generalized to the larger population.
III) Blocking can be used to reduce the within-treatment variability.

A) III only
B) I and III
C) I, II, and III
D) I only
E) II only

Question 37

Does donating blood lower cholesterol levels? 50 volunteers have a cholesterol test, then donate
Blood, and then have another cholesterol test. Which aspect of experimental design is present?

A) randomization
B) blinding
C) a placebo
D) a control group
E) none of these

Question 38

A basketball player has a 70% free throw percentage. Which plan could be used to simulate the
Number of free throws she will make in her next five free throw attempts?
I) Let 0,1 represent making the first shot, 2, 3 represent making the second shot,…, 8, 9 represent
Making the fifth shot. Generate five random numbers 0-9, ignoring repeats.
II) Let 0, 1, 2 represent missing a shot and 3, 4,…, 9 represent making a shot. Generate five random
Numbers 0-9 and count how many numbers are in 3-9.
III) Let 0, 1, 2 represent missing a shot and 3, 4,…, 9 represent making a shot. Generate five random
Numbers 0-9 and count how many numbers are in 3-9, ignoring repeats.

A) II and III
B) I only
C) II only
D) I, II, and III
E) III only

Question 39

Can watching a movie temporarily raise your pulse rate? Researchers have 50 volunteers check
Their pulse rates. Then they watch an action film, after which they take check their pulse rates once
More. Which aspect of experimentation is present in this research?

A) a control group
B) none of these
C) a placebo
D) randomization
E) blinding

Question 40

Among a dozen eggs, three are rotten. A cookie recipe calls for two eggs; they'll be selected
Randomly from that dozen. Which plan could be used to simulate the number of rotten eggs that
Might be chosen?
I) Let 0, 1, and 2 represent the rotten eggs, and 3, 4, …, 11 the good eggs. Generate two random
Numbers 0-11, ignoring repeats.
II) Randomly generate a 0, 1, or 2 to represent the number of rotten eggs you get.
III) Since 25% of the eggs are rotten
Generate two random numbers
0-3 and see how may 0's you get.

A) I, II, and III
B) III only
C) I only
D) I and III
E) II only

Question 41

Public opinion A member of the City Council has proposed a resolution opposing
construction of a new state prison there. The council members decide they want to assess
public opinion before they vote on this resolution. Below are some of the methods that are
proposed to sample local residents to determine the level of public support for the
resolution. Match each with one of the listed sampling techniques.
a. Place an announcement in the newspaper asking people to call their council
representatives to register their opinions. Council members will tally the calls they receive.
b. Have each council member survey 50 friends, neighbors, or co-workers.
c. Have the Board of Elections assign each voter a number, then select 400 of them using a
random number table.
d. Go to a downtown street corner, a grocery store, and a shopping mall; interview 100
typical shoppers at each location.
e. Randomly pick 50 voters from each election district.
f. Call every 500th person in the phone book.
g. Randomly pick several city blocks, then randomly pick 10 residents from each block.
h. Randomly select several city blocks; interview all the adults living on each block.

Question 42

Good CDs Brian is a systems manager for a large company. In his work, he has found that
about 5% of all CDs he orders are bad. He needs to give one of the executives at his
company five good CDs. Conduct a simulation to estimate how many CDs Brian will have
to check to get five good CDs for the executive.
a. Describe how you will use a random number table to conduct this simulation.
b. Show three trials by clearly labeling the random number table given below. Specify the
outcome for each trial.
c. State your conclusion.

Question 43

A statistics teacher wants to know how students in her school feel about mathematics courses. She decides to administer a
survey to a random sample of students taking a mathematics course. She has several sampling plans to choose from.
a. There are four ranks of students taking the class: freshmen, sophomores, juniors, and seniors. Randomly select 15 students
from each class rank.
b. Randomly select ten math class sections and survey every student in each of those sections.
c. Each student has a nine-digit student number. Randomly choose 60 different nine-digit numbers and survey the students
that correspond to those numbers.
d. Randomly select a number from 1 to 5. Using the class roster, start at that number, then select every fifth student from the
list after that.
Name the sampling strategy in each plan.

Question 44

Doors When trying to reduce energy costs for a home, one strategy is to install high quality
doors. A consumer service wants to test two brands (A and
B) of doors to see which is more
effective at preventing loss of heat. They have four doors of each brand they will install in a
small cabin built for this purpose. The cabin has places for four doors on the north wall and
four on the south wall. The inside of the cabin will be heated, and monitors will be placed
outside each door to measure the amount of heat loss.

a. Use the random numbers given to decide which doors to to put in which position.
Explain your method clearly.

b. Briefly explain why your assignment strategy is important in helping the manager assess
the effectiveness of the doors.

Question 45

Administrators at a large hospital are concerned about the possibility of drug abuse by people who work there. They decide
to check on the extent of the problem by having a random sample of the employees undergo a drug test. Several plans for
choosing the sample are proposed.
a. There are four employee classifications: doctors, medical staff (nurses, technicians, etc.) office staff, and support staff
(custodians, maintenance, etc.). Randomly select ten people from each category.
b. Each employee has a 4-digit ID number. Randomly choose 40 numbers.
c. At the start of each shift, choose every tenth person who arrives for work.
d. Randomly select five departments and test all the people who work in those department - doctors, nurses, technicians,
clerks, custodians, etc.
Listed below are the names of the 20 pharmacists on the hospital staff. Use the random
numbers listed below to select three of them to be in the sample. Clearly explain your
method.

Question 46

A tree farmer hires a botanist to evaluate a blight that seems to be affecting his trees. The trees are planted in horizontal rows
on a hill and the blight seems to be a bigger problem near the bottom of the hill. The farmer wants to know the extent of the
damage to the trees. Since the trees must be destroyed to examine them, the botanist doesn't have time to examine all the
trees, so she will select a sample. Several plans for choosing the sample are proposed.
a. Randomly select three trees from each horizontal row.
b. Lay out a grid on a map of the hill. Randomly select eight squares from the grid, and check all trees in those squares.
c. Randomly pick a number from 1 to 30. Start at the tree at that position in the first row, then go to every 30th tree after that.
d. Check the ten trees closest to the parking lot where the botanist parks her car.
Describe the kind of bias that might be present if the administration decides that instead of
subjecting people to random testing they'll just…
a. drop grains of rice on the aerial photo of the hill and inspect the trees that had rice land
on them.
b. ask the farmer to choose which trees he would like tested.

Question 47

Property taxes Administrators of the fire department are concerned about the possibility of
implementing a new property tax to raise moneys needed to replace old equipment. They
decide to check on public opinion by having a random sample of the city's population.
a. Several plans for choosing the sample are proposed. Match each plan with the letter
corresponding to the sampling strategy.
_____i. The city has five property classifications: single family homes, apartments,
condominiums, temporary housing (hotel and campgrounds), and retail property.
Randomly select ten residents
from each category.
_____ii. Each property owner has a 5-digit ID number. Use a random number table to
choose forty numbers.
_____iii. At the start of each week, survey every tenth person who arrives at the city park.
_____iv. Randomly select 20 city blocks and survey all the residents in each block.
_____v. Have each firefighter survey 10 of his/her neighbors.
A. convenience
B. stratified
C. simple
D. cluster
E. systematic
b. Name and briefly describe the kind of bias that might be present if the administration
decides that instead of selecting people randomly they'll just…
i. interview people about the new property tax at a fire station open house.
ii. ask people who are willing to be taxed to sign a petition.

Question 48

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.
Identify the subjects.

Question 49

A statistics teacher wants to know how students in her school feel about mathematics courses. She decides to administer a
survey to a random sample of students taking a mathematics course. She has several sampling plans to choose from.
a. There are four ranks of students taking the class: freshmen, sophomores, juniors, and seniors. Randomly select 15 students
from each class rank.
b. Randomly select ten math class sections and survey every student in each of those sections.
c. Each student has a nine-digit student number. Randomly choose 60 different nine-digit numbers and survey the students
that correspond to those numbers.
d. Randomly select a number from 1 to 5. Using the class roster, start at that number, then select every fifth student from the
list after that.
If the teacher in simply surveyed all of her students, what kind of sampling would that be?
Explain why this method is biased. Be sure to name the kind(s) of bias you describe and
link it to the variable of interest.

Question 50

A large manufacturer of batteries knows that, historically, 10% of its batteries come off the production line defective, and the
remaining 90% of batteries come off the production line in working condition. Conduct a simulation to estimate how many
batteries the company needs to pull off the production line in order to be sure of ending up with 10 working batteries.
Show three trials by clearly labeling the random number table given below. Specify the
outcome of each trial.

Question 51

Management at a large retail chain is concerned about the possibility of drug abuse by people who work there. They decide
to check on the extent of the problem by having a random sample of the employees undergo a drug test. Several plans for
choosing the sample are proposed.
a. Randomly select ten stores around the country and survey all the employees that work at those stores.
b. Choose the fourth person that arrives to work for each shift.
c. There are four employee classifications: supervisors, fulltime clerks, part-time clerks, and maintenance staff. Randomly
select ten people from each category.
d. Each employee has a three-digit identification number. Randomly choose 40 numbers.
One manager suggesting just going to the stores in the city where the company is
headquartered so they wouldn't have to travel far. What type of sampling would this be?
Explain why this method is biased. Be sure to name the kind(s) of bias you describe and
link it to the variable of interest.

Question 52

On January 1 of every year, many people watch the Rose Parade on television. The week before the parade is very busy for
float builders and decorators. Roses, carnations, and other flowers are purchased from around the world to decorate the
floats. Based on past experience, one float decorator found that 10% of the bundles of roses delivered will not open in time for
the parade, 20% of the bundles of roses delivered will have bugs on them and be unusable, 60% of the bundles of roses will
turn out to be beautiful, and the rest of the bundles of roses delivered will bloom too early and start to discolor before
January 1. Conduct a simulation to estimate how many roses the float decorator will need to purchase to have 15 good
bundles of roses to place on the float.
State your conclusion

Question 53

Aggressiveness A recent study evaluated elementary age children for aggressiveness. This
study found that the children who played video games were more likely to engage in
aggressive or violent play at school. The researchers said the difference was statistically
significant.
a. Briefly explain what "statistically significant" means in this context.
b. The news media reported that this study proved that playing computer games causes
children to be aggressive or violent. Briefly explain why this conclusion is not justified.
c. But perhaps it is true. We wonder if playing computer games can lead to aggressive or
violent behavior in elementary school children. We find 50 young children whose families
volunteer to participate in our research. Design an appropriate experiment. (You need not
explain how to randomize.)

Question 54

UFOs. A National Geographic survey in 2012 found that 36% of Americans believe in
aliens. (The outer-space kind, not visitors from foreign countries!) If you were to randomly
select 10 Americans, what is the average number of believers you'd expect in your sample?
Conduct a simulation to find out!
a. Explain how you will use the random numbers listed below to conduct your simulation.
b. Carefully label your simulation for 2 trials.
c. State your conclusion.

Question 55

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 assigned 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.
Is this study blind?

Question 56

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 assigned 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.
Describe a disadvantage of using volunteers in this study.

Question 57

College students' spending A consumer group wants to see if a new education program
will improve the spending habits of college students. Students in an economics class are
randomly assigned to three different courses on spending habits.
a. What are the experimental units?
b. How many factors are there?
c. How many treatments are there?
d. What is the response variable?

Question 58

Sweet potato pie Sam is preparing sweet potato pies as his dessert for Thanksgiving. The
store he shops at sells six sweet potatoes in a bag. He has found that each bag will contain
0, 1, or 2 bad sweet potatoes. Based on experience he estimates that there will be no bad
sweet potatoes in 40% of the bags, one bad sweet potato in 30% of the bags, and two bad
sweet potatoes in the rest. Conduct a simulation to estimate how many bags Sam will have
to purchase to have three dozen sweet good potatoes.
a) Describe how you will use a random number table to conduct this simulation.
b) Show two trials by clearly labeling the random number table given below. Specify the
outcome for each trial.
c) State your conclusion.

Question 59

M&Ms The Mars candy company starts a marketing campaign that puts a plastic game
piece in each bag of M&Ms. 25% of the pieces show the letter "M", 10% show the symbol
"&", and the rest just say "Try again". When you collect a set of three symbols "M", "&", and
"M" you can turn them in for a free bag of candy. About how many bags will a consumer
have to buy to get a free one? Use a simulation to find out.
a. Explain how you will use the random numbers listed below to conduct your simulation.
b. Carefully label your simulation for 2 trials.
c. State your conclusion.

Question 60

As a 4-H project, Billy is raising chickens. He feeds and waters them every day, and collects the eggs every other day, selling
them to people in the neighborhood. He has found that each hen's nest will contain from 0 to 2 eggs. Based on past
experience he estimates that there will be no eggs in 10% of the nests, one egg in 30% of the nests, and 2 eggs in the other 60%.
Conduct a simulation to estimate how many nests Billy will have to visit to collect a dozen eggs.
Describe how you will use a random number table to conduct this simulation.

Question 61

Announcements. A high school in Wisconsin stopped having announcements read to
students over the intercom system, choosing to have announcements displayed on
television monitors located throughout the building. To see how students feel about the
new system the principal wants to conduct a survey. Explain how to select a sample of
about 500 students using each sampling method below:
a. Simple random sample
b. Stratified random sample with grade levels as strata
c. Cluster sample with classrooms as clusters

Question 62

On January 1 of every year, many people watch the Rose Parade on television. The week before the parade is very busy for
float builders and decorators. Roses, carnations, and other flowers are purchased from around the world to decorate the
floats. Based on past experience, one float decorator found that 10% of the bundles of roses delivered will not open in time for
the parade, 20% of the bundles of roses delivered will have bugs on them and be unusable, 60% of the bundles of roses will
turn out to be beautiful, and the rest of the bundles of roses delivered will bloom too early and start to discolor before
January 1. Conduct a simulation to estimate how many roses the float decorator will need to purchase to have 15 good
bundles of roses to place on the float.
Describe how you will use a random number table to conduct this simulation.

Question 63

For a school project, Max must design a survey. For his survey he plans to randomly select families and gather information
about all the children in each of those families. He must have at least 20 children in his sample. The number of children per
family in the U.S. is given in the table below. How many families should Max expect to survey to reach at least 20 children?
(treat "5 or more" as 5.)
Show three trials by clearly labeling the random number table given below. Specify the
outcome for each trial.

Question 64

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. Plan 1: 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.
Design an experiment to determine whether the diet and exercise programs are effective in
helping dogs to lose weight.

Question 65

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

Question 66

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 assigned 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.
Describe an advantage of the placebo.

Question 67

Political math A recent study by Yale professors found that people's ability to do
mathematics computations got worse when the result went against the person's political
ideology. This was based on a randomized experiment in which people were given the
same basic computation, but some were given the question in a politically neutral context
and others were given the same computation in a context in which the correct answer went
against their political ideology. The difference between the proportion of people who got
the question wrong in a 'neutral' context and those who got the question wrong in a
'political' context was reported to be "statistically significant."
a. Briefly explain what "statistically significant" means in this context.
b. Would it be appropriate for the news media to report that the political context caused the
poor computational results? Explain.

Question 68

For a school project, Max must design a survey. For his survey he plans to randomly select families and gather information
about all the children in each of those families. He must have at least 20 children in his sample. The number of children per
family in the U.S. is given in the table below. How many families should Max expect to survey to reach at least 20 children?
(treat "5 or more" as 5.)
Describe how you will use a random number table to conduct this simulation.

Question 69

A statistics teacher wants to know how students in her school feel about mathematics courses. She decides to administer a
survey to a random sample of students taking a mathematics course. She has several sampling plans to choose from.
a. There are four ranks of students taking the class: freshmen, sophomores, juniors, and seniors. Randomly select 15 students
from each class rank.
b. Randomly select ten math class sections and survey every student in each of those sections.
c. Each student has a nine-digit student number. Randomly choose 60 different nine-digit numbers and survey the students
that correspond to those numbers.
d. Randomly select a number from 1 to 5. Using the class roster, start at that number, then select every fifth student from the
list after that.
Name and describe the kind of bias that might be present if the statistics teacher decides
that instead of randomly selecting students to survey on how they feel about the course she
just…
a. asks students to volunteer for the survey.
b. gives the survey during class one day.

Question 70

As a 4-H project, Billy is raising chickens. He feeds and waters them every day, and collects the eggs every other day, selling
them to people in the neighborhood. He has found that each hen's nest will contain from 0 to 2 eggs. Based on past
experience he estimates that there will be no eggs in 10% of the nests, one egg in 30% of the nests, and 2 eggs in the other 60%.
Conduct a simulation to estimate how many nests Billy will have to visit to collect a dozen eggs.
State your conclusion.

Question 71

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.
Identify the response variable.

Question 72

Grape juice and blood pressure Researchers who wanted to see if drinking grape juice
could help people lower their blood pressure got 120 non-smokers to volunteer for a
study. They measured each person''s blood pressure and then randomly divided the
subjects into two groups. One group drank a glass of grape juice every day while the other
did not. After sixty days the researchers measured everyone's blood pressure again. They
reported that differences in changes in blood pressure between the groups were not
statistically significant.
a. Was this an experiment or an observational study? Explain briefly.
b. Briefly explain what "not statistically significant" means in this context.
c. Briefly explain why the researchers randomly assigned the subjects to the groups.
d. Since everyone's blood pressure was measured at the beginning and at the end of the
study, the researchers could have simply looked at the grape juice drinkers to see if their
blood pressure changed. Briefly explain why the researchers bothered to include the
control group.
e. Briefly explain why the researchers studied only non-smokers.
f. Other researchers now plan to replicate this study using both smokers and non-smokers.
Briefly describe the design strategy you think they should use.

Question 73

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 assigned 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.
Describe an advantage to random assignment of treatment.

Question 74

Video games A headline in a local newspaper announced "Video game playing can lead to
better spatial reasoning abilities." The article reported that a study found "statistically
significant differences" between teens who play video games and teens who do not, with
teens who play video games testing better in spatial reasoning. Do you think the headline
was appropriate? Explain.

Question 75

Insulators Ceramics engineers are testing a new formulation for the material used to make
insulators for power lines. They will try baking the insulators at four different
temperatures, followed by either slow or rapid cooling. They want to try every
combination of the baking and cooling options to see which produces insulators least likely
to break during adverse weather conditions.
a) What are the experimental units?
b) How many factors are there?
c) How many treatments are there?
d) What is the response variable?

Question 76

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. Plan 1: 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.
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

Question 77

Management at a large retail chain is concerned about the possibility of drug abuse by people who work there. They decide
to check on the extent of the problem by having a random sample of the employees undergo a drug test. Several plans for
choosing the sample are proposed.
a. Randomly select ten stores around the country and survey all the employees that work at those stores.
b. Choose the fourth person that arrives to work for each shift.
c. There are four employee classifications: supervisors, fulltime clerks, part-time clerks, and maintenance staff. Randomly
select ten people from each category.
d. Each employee has a three-digit identification number. Randomly choose 40 numbers.
Name the sampling strategy in each plan.

Question 78

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 assigned 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.
Identify the treatments.

Question 79

A large manufacturer of batteries knows that, historically, 10% of its batteries come off the production line defective, and the
remaining 90% of batteries come off the production line in working condition. Conduct a simulation to estimate how many
batteries the company needs to pull off the production line in order to be sure of ending up with 10 working batteries.
Describe how you will use a random number table to conduct this simulation.

Question 80

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.
Identify the treatments.