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 placebo
E) a control group

Accepted Answer

The scenario describes a before-and-after study on the same group of volunteers without any mention of randomization, blinding, placebo, or a separate control group.

Question 2

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 medication type.
D) uses matched pairs.
E) has one factor (medication) blocked by age.

Accepted Answer

The answer of A researcher wants to compare the performance...

Question 3

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

Accepted Answer

The survey design suffered from non-response bias as only one-third of the surveys were returned, and the 44% is a statistic, not a parameter, because it is based on a sample, not the entire population.

Question 4

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?

Accepted Answer

The answer of Insulators Ceramics engineers are testing a new...

Question 5

In an experiment the primary purpose of blinding is to reduce …
A) randomness.
B) bias.
C) variation.
D) undercoverage.
E) confounding.

Accepted Answer

Blinding is used to prevent bias by ensuring that participants and/or researchers do not know which treatment is being administered, thus preventing their expectations from influencing the results.

Question 6

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) experiment
C) census
D) observational study
E) SRS

Accepted Answer

A census involves collecting data from every member of the population, which in this case would mean gathering PSAT scores from all boys and girls taking AP Statistics at the high school, ensuring complete and accurate comparison.

Question 7

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

Accepted Answer

The population of interest is indeed the people who read the magazine, and the random sample should provide a reasonably accurate estimate of the percentage of all subscribers who use supplements. However, "64%" is a statistic, not a parameter.

Question 8

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

Accepted Answer

This is a prospective study because it involves following subjects over time to observe future outcomes.

Question 9

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

Accepted Answer

Sampling error is usually reduced when the sample size is larger, and it is the result of random variations and is always present. A census can still have biases due to non-sampling errors.

Question 10

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.

Accepted Answer

The answer of Grape juice and blood pressure Researchers who...

Question 11

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) simulation
D) census
E) experiment

Accepted Answer

A census involves collecting data from every member of the population, which is the most accurate way to compare the average ages of all math and science teachers at the high school.

Question 12

Moods A headline in the New York Times announced "Research shows running can alter
one's moods". The article reported that researchers gave a Personality Assessment Test to
231 males who run at least 20 miles a week, and found "statistically significant personality
differences between the runners and the male population as a whole." Do you think the
headline was appropriate? Explain.

Accepted Answer

The answer of Moods A headline in the New York...

Question 13

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

Accepted Answer

This is a prospective study because the researcher follows the participants over time to observe future outcomes, specifically the rate of heart attacks in this case.

Question 14

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?

Accepted Answer

The answer of Cloning A polling organization is investigating public...

Question 15

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

Accepted Answer

Bias results from a sampling method likely to produce samples that do not represent the population, not from random variation. Increasing sample size does not reduce bias; it reduces random error.

Question 16

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.

Accepted Answer

The answer of Property taxes Administrators of the fire department...

Question 17

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 each wrestler is equally likely to be chosen.
E) Yes, because stratified samples are a type of simple random sample.

Accepted Answer

A simple random sample requires that every possible group of 32 wrestlers has an equal chance of being selected, which is not the case here since exactly two wrestlers are chosen from each team.

Question 18

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 the toys were selected at random.
D) Yes, because a stratified sample is a type of simple random sample.
E) No, because not all combinations of 100 toys could have been chosen.

Accepted Answer

The sample is not a simple random sample because it was stratified by selecting 5 toys from each assembly line, meaning not all combinations of 100 toys could be chosen.

Question 19

Which is not a critical part of designing a good experiment?
A) Random selection of subjects.
B) Control of known sources of variability.
C) All of these are important.
D) Replication of the on a sufficient number of subjects.
E) Random assignment of subjects to treatments.

Accepted Answer

The answer of Which is not a critical part of...

Question 20

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.

Accepted Answer

The answer of Sweet potato pie Sam is preparing sweet...

Quiz 8: Regression, Associations, and Predictive Modeling

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?

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

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?

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

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.

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?

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.

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 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?

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