Deck 3: Displaying and Describing Categorical Data

Question 1

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

Answer 1

A

Question 2

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

Answer 2

A

Question 3

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

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

Answer 3

A

Question 4

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 5

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

Question 6

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

Question 7

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 the veterinarians were asked to inspect the animals for fleas and evidence of flea bites. This experiment is...

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

Question 8

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

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

Question 9

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 the men for several years to see if there was any difference between the groups in the rate of heart attacks. This is a(n)
…

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

Question 10

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

Question 11

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

Question 12

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) is completely randomized.
C) has one factor (age) blocked by type of medication.
D) uses matched pairs.
E) has one factor (medication) blocked by age.

Question 13

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 the subjects for 10 years to see which group develops more cancer. This is a

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

Question 14

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

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

Question 15

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

Question 16

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

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

Question 17

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) survey
C) prospective study
D) matched experiment
E) randomized experiment

Question 18

In an experiment the primary purpose of blocking is to reduce

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

Question 19

In an experiment the primary purpose of blocking is to

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

Question 20

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

Question 21

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 22

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.

Question 23

Placebos are a tool for

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

Question 24

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

Question 25

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 26

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

Question 27

Of the following, which is not a critical part of designing a good experiment?

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

Question 28

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

Question 29

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 30

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) observational study
C) sample survey
D) census
E) experiment

Question 31

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 32

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 Bill will have to visit to collect a dozen eggs.

-Show three trials by clearly labeling the random number table given below. Specify the outcome for each trial.

$\begin{array}{llllll}57528 & 78305 & 63508 & 29418\\ 90676&31993 & 54636&17877\\31574 &28042 & 72621& 84818 \end{array}$

Question 33

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 check their pulse rates once more. Which aspect of experimentation is present in this research?

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

Question 34

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 35

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 36

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 37

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 38

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

Question 39

Military funding A college group is investigating student opinions about funding of the military. They phone a random sample of students at the college, asking each person one of these questions (randomly chosen):
A: "Do you think that funding of the military should be increased so that the United States can better protect its citizens?"
B: "Do you think that funding of the military should be increased?"
Which question do you expect will elicit greater support for increased military funding? Explain. What kind of bias is this?

Question 40

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.)

$\begin{array}{|l|l|l|l|l|l|l|}\hline \text { No. of Children }& 0 & 1 & 2 & 3 & 4 & 5 \text { or more} \\\hline \% \text { of families} & 17 & 23 & 25 & 16 & 10 & 9 \\\hline\end{array}$


-State your conclusion.

Question 41

Name and describe the kind of bias that might be present if the management decides that instead of subjecting people to random testing they'll just…
a. Hold department meetings and drug test the employees that attend.
b. Offer additional employee discounts for those employees who agree to be drug tested.

Question 42

Identify the subjects.

Question 43

Explain why the last plan suggested above, selecting the ten trees closest to the parking lot, might be biased. Be sure to name the kind(s) of bias you describe and link it to the variable of interest.

Question 44

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 45

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. Name the sampling strategy in each.
a. Randomly select three trees from each orizontal 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.

Question 46

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.

$\begin{array}{|l|l|}\hline 1 & \text {cluster} \\\hline 2 &\text { convenience} \\\hline 3 & \text {judgment} \\\hline 4 &\text { multistage} \\\hline 5 & \text {simple (SRS)} \\\hline 6 & \text {stratified }\\\hline 7 & \text {systematic }\\\hline 8 & \text {voluntary response} \\\hline\end{array}$
_ 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 47

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 Bill will have to visit to collect a dozen eggs.

-Describe how you will use a random number table to conduct this simulation.

Question 48

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 49

A statistics teacher wants to know how her students 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. Name the sampling strategy in each.
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.

Question 50

Is this study blind?

Question 51

Candy packaging Marketing researchers wonder if the color and type of a candy's packaging may influence sales of the candy. They manufacture test packages for chocolate mints in three colors (white, green, and silver) and three types (box, bag, and roll). Suspecting that sales may depend on a combination of package color and type, the researchers prepare nine different packages, then market them for several weeks in convenience stores in various locations. In this experiment,
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 52

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.)

$\begin{array}{|l|l|l|l|l|l|l|}\hline \text { No. of Children} & 0 & 1 & 2 & 3 & 4 & 5 \text {or more} \\\hline \% \text {of families} & 17 & 23 & 25 & 16 & 10 & 9 \\\hline\end{array}$

-Describe how you will use a random number table to conduct this simulation.

Question 53

Property taxes Administrators of the fire department are concerned about the possibility of implementing a new property tax to raise money 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. Write the letter corresponding to the sampling strategy in the blank next to each plan.

A. convenience; B. stratified; C. simple; D. cluster; E. systematic
___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 a housing classification (say, apartments) and survey all the people who
live in that property classification.
___ v. Have each firefighter survey 10 of his/her neighbors.

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 54

Gun control Two friends who strongly disagree on whether there should be stricter regulation of guns in this country want to conduct a poll of the students in their school to see which side most students agree with. Each came back with a different version of the question they want to ask.
Version 1: Do you think the government should respect our 2nd Amendment rights and allow lawabiding citizens to own guns?
Version 2: In the wake of recent mass shootings, should laws be passed to keep guns out of the hands of people with a history of violence?
a. Which version would make it seem like people oppose stricter gun regulation? What kind of bias is this?
b. Is the version you did not pick in part a less biased?
c. Is it reasonable for a person to respond 'yes' to both questions?

Question 55

Telephone poll The City Council decides to conduct a telephone poll. Pollsters ask a carefully chosen random sample of adults this question: "Do you favor the construction of a new prison to deal with the high level of violent crime in our State?" In what way might the proportion of "Yes" answers fail to accurately reflect true public opinion? Explain briefly. What kind of bias is this?

Question 56

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.

$\begin{array}{|c|c|c|}\hline \text {Trial }& \text { Simulation} & \text { Outcome} \\\hline \# 1 & 03242\quad50692\quad18977\quad28370 & \\\hline \# 2 & 78695\quad21402\quad85525\quad81183 & \\\hline \# 3 & 60809\quad06765\quad39996\quad81915 & \\\hline\end{array}$

c. State your conclusion.

Question 57

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 58

Preservative Leather furniture used in public places can fade, crack, and deteriorate rapidly. An airport manager wants to see if a leather preservative spray can make the furniture look good longer. He buys eight new leather chairs and places them in the waiting area, four near the south-facing windows and the other four set back from the windows as shown. He assigned the chairs randomly to these spots.
a. Use the random numbers given to decide which chairs to spray. Explain your method clearly.
$32219 \quad 00597 \quad 86374$

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

Question 59

Cloning A polling organization is investigating public opinion about cloning. They phone a random sample of 1200 adults, asking each person one of these questions (randomly chosen):
A: "Do you favor allowing doctors to use cloned cells in attempts to find cures for such terrible diseases as Alzheimer's, diabetes, and Parkinson's?"
B: "Should research scientists be allowed to use cloned human embryos in their experiments?"
Which question do you expect will elicit greater support for cloning? Explain. What kind of bias is this?

Question 60

Survey. A local news station wants to know what percentage of people favor investing in new public light-rail system for the city. They conduct a survey, calling homes between
10:00 a.m. and 3:00 p.m. Explain why this sampling plan is biased.

Question 61

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.


-Show three trials by clearly labeling the random number table given below. Specify the outcome for each trial. $\begin{array}{lllllllllll}37542 & 04805 & 64894 & 74296 & 24805 & 24037 & 20636 & 10402 & 00822 \\ 08422 & 68953 & 19645 & 09303 & 23209 & 02560 & 15953 & 34764 & 35080 \\ 99019 & 02529 & 09376 & 70715 & 38311 & 31165 & 88676 & 74397 & 04436 \\ 12807 & 99970 & 80157 & 36147 & 64032 & 36653 & 98951 & 16877 & 12171\end{array}$

Question 62

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

Question 63

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 64

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.

-Describe an advantage of the placebo.

Question 65

Listed at the right are the names of twenty full-time clerks on the retail staff. Use the random numbers listed below to select four of them to be in your sample. Clearly explain your method.

$\begin{array}{llll}18192 & 95318 & 02975 & 01191\\29958&09275&89141&61909\end{array}$


$\begin{array}{|c|c|c|c|}\hline \text {Larry }& \text {Marissa }& \text {Tim }&\text { Diane} \\\hline \text {Carol }& \text {Joshua} & \text {Barbara} &\text { Allan} \\\hline \text {Rich }&\text { Sharyn }&\text { Brian }&\text { Kelly} \\\hline \text {Nicole} &\text { John} & \text {June} &\text { Frank} \\\hline \text {Steve} & \text {Andrea} & \text {Matthew} &\text { Erin} \\\hline\end{array}$

Question 66

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

Question 67

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.

-Describe a disadvantage of using volunteers in this study.

Question 68

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 69

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.


-Describe an advantage to random assignment of treatment.

Question 70

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.)

$\begin{array}{|l|l|l|l|l|l|l|}\hline\text { No. of Children} & 0 & 1 & 2 & 3 & 4 & 5\text { or more} \\\hline\text {\% of families} & 17 & 23 & 25 & 16 & 10 & 9 \\\hline\end{array}$


-Show three trials by clearly labeling the random number table given below. Specify the outcome for each trial.

$\begin{array}{llllll}84432 & 04916 & 52949 & 78533 & 62350 & 20584 \\ 56367 & 19701 & 58765 & 41760 & 43304 & 13399 \\ 97198 & 40974 & 45301 & 60177 & 35604 & 21580\end{array}$

Question 71

One administrator suggested walking into the break room and testing the people in there.
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 72

Administrators at a 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. Name the sampling strategy in each.
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 a department (say, radiology) and test all the people who work in that department - doctors, nurses, technicians, clerks, custodians, etc.

Question 73

State your conclusion.

Question 74

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.


-Explain how replication would be used in this study.

Question 75

Name and 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. interview employees about possible drug abuse.
b. ask people to volunteer to be tested.

Question 76

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.

-Describe an advantage to random assignment of treatment.

Question 77

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 78

There are 1,237 trees on the hill. Explain how to use a random digit table to select a simple random sample of 20 trees. Then use the random digit table below to select the first five trees for your sample.
$\begin{array}{lllll}04905 & 8852 & 29350 & 91397 & 94531&78981&81980&08530\\19994&65142&05087&11232&39129&49559&94540&24070\end{array}$

Question 79

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 factors and levels.

Question 80

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.