AP Review Questions 121-170

Question 1

A farmer wishes to study the effect of three different fertilizers on crop yields. Then he randomly assigns the three different fertilizers to one of the four pots. One plot receives no fertilizer. The plots are harvested after a growing period and yields are measured and compared. Which of the following statements best describes the design of the study?
I. This design has matched pairs.
II. This design has blocks.
III. This is a completely randomized design.
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 1

(E) III only

Completely randomized design because the treatments are randomized to the experimental units.

Question 2

Which of the following statements is true about completely randomized design?
I. It replicates treatments to paired groups with similar experimental units.
II. Treatments are assigned haphazardly to experimental units.
III. It controls for the effects of lurking variables.
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 2

(E) III only.

Completely randomized design controls for lurking variables.

Question 3

Which of the following statements is true about block design?
I. Treatments are assigned haphazardly to experimental units.
II. It controls for the effects of confounding variables.
III. Experimental units are examined before receiving treatments.
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 3

(D) II only
Block design controls for confounding variables, which are variables that cannot be separated from the treatment variable.

Question 4

Which of the following statements is true about matched-pairs design?
I. It is a type of block design.
II. It uses the same or similar experimental units with different treatments.
III. Treatments are assigned haphazardly to experimental units.
(A) I only
(B) I and III only
(C) I and III only
(D) II only
(E) III only

Answer 4

(C) I and II only. Matched-pairs design controls for variation in experimental units by either reusing them or by pairing experimental units by similar characteristics and separating them into different treatment groups.

Question 5

A woman insists that she can detect whether tea was poured into milk or whether milk was poured into tea. An experiment is devised. In the kitchen, six cups are labeled A,B,C,D,E, and F. Which cups receive milk poured into tea is decided by a series of coin flips and recorded. The woman is asked to taste each cup and identify the type of preparation. Which of the following statements best describes the design of the study?
I. Double-blind experiment
II. Block Design
III. Completely randomized design
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 5

(E) III only. Treatments are randomized to the experimental units.

Question 6

A pharmaceutical research company wishes to find the optimal dosage of a drug. The dosages are 250 mg, 500 mg, 750 mg, and 1000 mg. In Russia, 1000 experimental subjects are recruited and divided into five groups. The researchers first determine the subjects' height, weight, blood pressure, and gender. Using these metrics, they select five similar individuals and randomly assign each one to one of the five groups. Dosages are then randomly assigned to the groups, with one group receiving a placebo. The participants and researchers are not informed of the assignment of dosages. Which of the following statements best  describes the design of the study?
I. Block design
II. Observational Study
III. Double-blind experiment
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 6

(B) I and III only.
The researchers matched experimental units based on physical characteristics that might influence the effect from the medicine.

Question 7

The purpose of doing an experiment is to:
(A) Determine cause and effect
(B) Identify confounding variables
(C) Identify lurking variables
(D) Control participants
(E) Find human error

Answer 7

(A)Statistical methods only identify relationships

Question 8

The purpose of blocking in experimental design is to:
(A) Control for confounding variables
(B) Control experimenter bias
(C) Control for lurking variables
(D) Replicate the experiment
(E) Organize experimental units

Answer 8

(A) The purpose of experimental design is to anticipate and control variation. Block design targets variation from confounding variables by grouping to control the variation

Question 9

The purpose of matched-pairs design is to:
(A) Control experimenter bias
(B) Control for lurking variables
(C) Control for confounding variables
(D) Replicate the experiment
(E) Organize experimental units

Answer 9

(C)The purpose of experimental design is to anticipate and control variation. Matched-pairs design specifically targets variation from confounding variables. BY pairing, variation stemming from a confounding variable can be detected

Question 10

Suppose you wish to study the effects of high-protein kibble on adult dog behavior. What would be the best design to determine between-group effects?
(A) Matched-pairs design
(B) Completely randomized design
(C) Block design
(D) Double-blind design
(E) Randomized design

Answer 10

(A) Since the comparison is between high-protein kibble and a control kibble, matched pairs would be the best design to detect between group differences or effects.

Question 11

Suppose you wish to study anti-aging effects of an oil extract on women over 50. One hundred participants apply the oil on the right side of their faces for six weeks. Then the researcher examines the right side against the left side for the effects of the oil. Which of the following statements best describes the design of the study?
I. Completely randomized design
II. Matched-pairs design
III. Block design
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 11

(D) II only. Matched-pairs design is the best description since there are only two treatments

Question 12

Suppose you want to study the effects of a new organic flea shampoo for dogs. You wish to advertise that it is as effective as the leading brand used by groomers. You have 100 beagles to work with and you have decided to use a completely randomized design. What process would be correct?
(A) Measure the shine of each beagle’s coat. Put the 50 shiniest in the group receiving the organic flea shampoo treatment and treat the others with the leading brand.
(B) Select pairs of beagles that have similar to identical coat characteristics. Flip a coin to decide which beagle is treated with the organic flea shampoo.
(C) Randomly assign the beagles to one of two groups. Then randomly assign the two treatments to the groups.
(D) List all the dogs’ names in alphabetical order and assign the first 50 to the organic flea shampoo treatment and the others to the leading brand.
(E) Randomly select 50 dogs to receive the organic flea shampoo. The rest receive the leading brand.

Answer 12

(C) The correct method is to randomly assign the dogs to one of the two groups. Then randomly assign the treatments

Question 13

A new drug for appetite control was tested on 1000 men and women using a completely randomized design. The researchers expected that the overall effect would be significant weight loss; however, they were disappointed when the group effects were insignificant. When they examined the results, they found that men gained weight while women lost weight on the new drug. What is the best explanation for the effects of this experiment?
(A) Experimenter bias was systematic when recording the results.
(B) A placebo effect interfered with the results.
(C) The scale used to measure the weights of men was broken.
(D) Gender is a confounding variable in this study.
(E) Gender is a lurking variable in the study.

Answer 13

(D) It appears that gender confounds the results for this appetite-control drug and that blocking by gender would control for the gender difference in respnse

Question 14

A new treadmill is compared with an older model. 1000 men and women are blocked by gender and randomly assigned to one of the two machines. Researchers measure each participant’s fitness level before the experiment. After a period of time, the researchers measure the participants assigned to the new treadmill are interviewed after the experiment, researchers learn that they did not follow the exercise schedule faithfully because the new treadmill was too complicated to operate. What is the best explanation for the outcomes of the study?
(A) Experimenter bias was systematic when recording the results.
(B) The operation of the new treadmill is a lurking variable in this study.
(C) The device used to measure the fitness levels of men was broken.
(D) A placebo effect interfered with the results.
(E) Gender is a confounding variable in this study.

Answer 14

(B) After the interviews, it is clear that the complicated operation of the new treadmill affected the outcomes and was not part of the investigation.

Question 15

Which of the statements describes good practices when designing experiments?
I. Control the effects of confounding variables.
II. Replicate to increase variation from treatments.
III. Randomize to ensure that an effect is observed.
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 15

(A) I only. The design of experiments anticipates confounding variables and controls for them by blocking.

Question 16

When the difference between what we expect and what we observe in a study is unusually large and cannot be attributed to chance, the finding is \_\_\_\_\_\_\_\_\_\_\_\_
(A) remarkable
(B) repeatable
(C) statistically significant
(D) insignificant
(E) systematic

Answer 16

(C) If the difference between what we expect and what we observe is too large to attribute to chance

Question 17

A new treatment for overactive teenagers called "talk-therapy" is tested on 20 teens. The teens are randomly assigned to two groups. Then one group is randomly assigned the talk-therapy treatment and the other group receives fake talk-therapy. If a teen knows that he or she is getting the real talk-therapy, he or she is less-active. When the researchers know they are measuring a teen who received talk-therapy, they systematically lower the ratings. Which type of design would be ideal for controlling for these problems?
I. Completely randomized design
II. Double-blind experiment
III. Match-pairs design
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 17

(D) II only. When the outcomes of an experiment are affected by the participants and researchers knowing who is receiving the real treatment, a double blinded experiment is appropriate and controls both researcher bias and placebo.

Question 18

What statements are true about statistical significance?
I. The difference between what is expected and what is observed is too large to attribute to chance alone.
II. It determines which experimental design to use.
III. It is determined numerically with hypothesis testing.
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 18

(B) When an effect is statistically significant, the difference between the expected and observed effect is too large to be attributed only to chance

Question 19

Under what conditions would it be necessary to conduct an observational study?
(A) When there aren’t any willing volunteers to participate in the study
(B) When the treatments aren’t effective in a laboratory?
(C) When the subjects can’t be randomly selected
(D) When it is unethical to improve a treatment in order to measure a response on subjects
(E) When the research is not sufficiently funded

Answer 19

(D) Observational studies are useful when it is unethical to experiment on subjects because of the adverse effects from treatment levels

Question 20

What are the advantages of an experiment over an observational study?
I. Outcomes will naturally change over time.
II. The researcher has more control of the environment and treatment.
III. There is more diversity in the sample of subjects.
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 20

(D) II only. An experiment has the advantage that the researcher can control the treatment levels and the environment that subjects are exposed to

Question 21

At a charter high school, administrators wish to collect a sample of 50 students. The proportions of the student body represented by each class are: 45% freshmen, 28% sophomores, 16% juniors and 11% seniors. They decide to randomly sample 23 freshmen, 14 sophomores, 8 juniors, and 5 seniors. Which of the following methods was used to select the probability sample?
(A) Random
(B) Systematic
(C) Stratified
(D) Cluster
(E) Simple Random

Answer 21

(C) That is a stratified sample because the population was first divided into sections and then randomly sampled from each section with the proportion from each block dictated by the population proportions

Question 22

The athletic department at a very large high school wishes to form a kickball team of 20 students from the entire student body. They run a lottery to select 20 students ID numbers from a thoroughly mixed bucket of tickets where each student is represented by one ticket. Which of the following methods was used to select the probability sample?
(A) Random
(B) Systematic
(C) Stratified
(D) Cluster
(E) Simple random

Answer 22

(E)This is a simple random sample because each member of the population has and equal chance of being chosen and all samples have an equal chance of being chosen from the population

Question 23

At the Westminster Dog Show, sponsors wish to measure the popularity of the booths in the retail area. Using a list of all attendees, a random number is generated to determine a starting position in the list and then every tenth attendee is placed in the sample. When the end of the list is reached, sampling continues from the top of the list. Sampling stops when the starting position is reached. Which of the following methods was used to select the probability sample?
(A) Random
(B) Systematic
(C) Stratified
(D) Cluster
(E) Simple random

Answer 23

(B) This is a systematic sample. Randomization is used to determine a starting position and then the entire population is sampled based on a well-defined pattern

Question 24

A charter school operator in LA wishes to gather information about student achievement. From the 73 small schools the operator manages, one school is selected by lottery and all students from that school are used in the sample. Which of the following methods was used to select the probability sample?
(A) Random
(B) Systematic
(C) Stratified
(D) Cluster
(E) Simple random

Answer 24

(D) This is a cluster sample. The individual schools are the sections and one of them is selected at random.

Question 25

The mathematics department wished to form a sample from each of 10 courses offered. They randomly select three individuals from each course and include them in the 30-person sample. Which of the following methods was used to select the probability sample?
(A) Random 
(B) Systematic
(C) Stratified
(D) Cluster
(E) Simple random

Answer 25

(A)This is a random sample because each of the three representatives from a course was selected randomly.

Question 26

You would like to determine the characteristics of Facebook users, so you examine the accounts of several Facebook friends and decide that your network of friends is similar to those you observe in other accounts. You use your friends as a sample to determine characteristics of Facebook users. Which of the following methods was used to select the nonrandom sample?
(A) Non-response
(B) Convenience
(C) Quota
(D) Cluster
(E) Self-selected or voluntary response

Answer 26

(B) This is a convenience sample because the friends that you have are easily sampled and you have decided to use them since they appear representative to you.

Question 27

In a statistics course, the instructor wishes to determine whether a new program for statistical analysis would be beneficial to students. He asks for 10 volunteers from the class to use the program in their final project and was used to select the nonrandom sample?
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 27

(E)This is a self-selected or voluntary response sample.

Question 28

A pollster wishes to determine which candidate is most popular among retirees on the issue of health care. Based on party registration proportions, the pollster selects a focus group of 30 retirees. Which of the following methods was used to select the nonrandom sample?
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 28

(C) This is a quota sample. The registration proportions are maintained but the attendees are selected according to their characteristics as retirees.

Question 29

Which of the following BEST describes the goal of sampling?
I. Produce an average sample.
II. Choose the average representatives.
III. Produce a representative sample.
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 29

(E) III only. The purpose of sampling is to gather a representative group.

Question 30

Street parking in your neighborhood is limited. You have amassed 10 parking tickets in one year and believe your neighbors have had a similar experience.You leave 50 postcards on the windshields of parked cars in your neighborhood asking for a response to one question with room for additional comments. You receive 48 responses, and 30 of the responses include elaborate descriptions of street parking issues. Which type of sampling bias BEST describes the situation?

Answer 30

(A) Voluntary response bias due to the fact that the respondents had strong feelings about the issue, which motivated them to respond.

Question 31

Local schools wish to add a bond measure to the ballet. They survey the residents with the following question: "Will you support the bond measure if it will cost the taxpayers $30 million in 30 years?" Three-fourths of respondents reply "No." Which type of sampling bias best describes the situation?
(A) Voluntary response
(B) Wording
(C) Response
(D) Researcher
(E) Non-response

Answer 31

(B) Wording bias. If the question had been rewritten the response would likely have been more favorable

Question 32

A credit card wishes to sample its customers to find out which features of the rewards program are preferred. Its call center schedules calls between 5:30 and 8:00 P.M. Only 25% of the customers the call center reaches are willing to participate. Which type of sampling bias best describes the situation?
(A) Voluntary response
(B) Wording
(C) Response
(D) Researcher
(E) Non-response

Answer 32

(E) Non-response bias which could be linked to the time of day the survey is conducted or to a lack of interest

Question 33

A study on sexual activity of students in a college dormitory showed that men reported five casual sexual encounters with women on average while women reported only two over the same time period. Which type of sampling bias BEST describes the situation?
(A) Voluntary response
(B) Wording
(C) Response
(D) Researcher
(E) Non-response

Answer 33

(C) Response bias: due to stereotypes held about sexuality, men and women both may have misrepresented their actual experience to the interviewer

Question 34

Which of the statements is true about experiments?
I. They impose treatments on subjects.
II. The researcher doesn’t attempt to manipulate a response.
III. The researcher wishes to determine an effect from a treatment.
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 34

(B) I and III only. In experiments, researchers impose treatments on experimental units or subjects in order to manipulate a response that can be linked to the treatments.

Question 35

Which of the statements is true about observational studies?
I.They impose treatments on subjects.
II. The researcher doesn’t attempt to manipulate a response.
III. The researcher wishes to determine an effect from a treatment
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 35

(D) II only. In observational studies, the researcher simply observes and records behavior.

Question 36

Which of the statements is true abut the placebo effect?
I. It is a response due to believing that a treatment is being administered.
II. It is an effect from a legitimate treatment.
III. It is a negative response due to a high dosage.
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 36

(A) I only. The placebo effect is when a treated person shows a benefit despite the fact that the treatment has no effective component.

Question 37

Which of the statements is true about a double-blind experiment?
I. Subjects are not aware whether they are receiving visible treatments.
II. It is a study of adolescent-onset blindness.
III. Researchers are not aware of the distribution of placebos or visible treatments.
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 37

(B) I and III only. When neither the subjects nor the researchers know which group are receiving treatments or placebos, the experiment is double-blind.

Question 38

In general, which of the following do researchers attempt to achieve when designing experiments?
I. Attempt to impose statistical control
II. Attempt to replicate an observational study
III. Attempt to randomize events
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 38

(A) I only. An experiment employs statistical control, which refers to a researcher holding constant variables that aren’t under study but could influence the outcomes.

Question 39

What is an appropriate method for performing randomization?
(A) Appropriately using a table of random digits to select participants or assign treatments.
(B) Haphazardly generating a list of digits to select participants or assign treatments.
(C) Using telephone numbers as random digits to select participants or assign treatments.
(D) Using a complicated mathematical function to select participants or assign treatments.
(E) Rearranging the digits to select participants or assign treatments.

Answer 39

(A) The appropriate method is to use a table of random digits or a random number generator

Question 40

Which of the statements is true about blocking?
I. Treatments are organized in the same way between blocks.
II. They are used to replicate treatments on the same subject.
III. Treatments are randomized within blocks.
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only

Answer 40

(E) III only. In blocking, treatments are randomized within blocks.

Question 41

If the difference between a treatment and control group is too big to attribute to chance, it is \_\_\_\_.
(A) Statistically significant
(B) Not significant
(C) Important
(D) A maximum
(E) Substantial

Answer 41

(A) When the differences between what we expect to find without treatment and what we find with treatment is too large to attribute to chance

Question 42

A researcher randomly selected 50 volunteers to participate in a study on weight and energy consumption. Each volunteer's weight and metabolic rate were recorded. This is an example of \_\_\_\_\_\_.
(A) An observational study
(B) A double-blind experiment
(C) A completely randomized experiment
(D) An experiment
(E) A block experiment

Answer 42

(A) This is an observational study because the subjects did not receive a treatment

Question 43

A researcher randomly selected 50 overweight volunteers to participate in a study on weight and energy consumption. Each volunteer's weight and metabolic rate were recorded.Then the researcher randomly assigned the subjects to one of two groups. One group received a metabolism-boosting supplement, and other group received the placebo. Neither the subjects nor the researchers knew who received the treatment or the placebo. This is an example of \_\_\_\_\_.
(A) An observational study
(B) A double-blind experiment
(C) A completely randomized experiment
(D) An experiment
(E) A block experiment

Answer 43

(B) When neither the subjects nor the researchers know who is receiving a treatment or a placebo, the experiment is double-blind

Question 44

A researcher randomly selected 50 online teachers to participate in a study on the effects of multitasking. Before the study began, teachers completed a survey that was used to determine a baseline rage index. Then the researcher randomly assigned teachers to one of two groups. One group was allowed to perform tasks such as grading assignments, responding to email and teaching classes in one-hour intervals, while the other group had to perform tasks whenever they were received or demanded, with priority given to students requesting tutoring. After a period of one month, teachers again completed the survey to measure their rage index. Which of the statements describes this study?
I. This is an experiment.
II. This is an observational study.
III. This is a matched-pairs design.
(A) I only
(B) I and III only
(C) II only
(D) I and II only
(E) III only

Answer 44

(B) I and III only. This is an experiment since the researcher imposed treatments on the groups.

Question 45

A researcher wishes to study the effects of diet on weight loss. He recruits 60 overweight subjects to participate in the study and records their gender. He also randomly assigns three different diet and exercise regimens to the subjects. Which of the following describes appropriate blocking techniques?
I. Block on gender
II. Block on diet
III. Block on exercise
(A) I only
(B) I and III only
(C) II only
(D) I and II only
(E) III only

Answer 45

(A) I only. Blocking should be done on gender to for the variability due to differences between males and females.

Question 46

A study on the yield of broccoli wishes to compare application of two fertilizers: one provides phosphate and the other nitrogen. The treatment levels are 0, 20, 40, and 60 pounds per acre.
(A) Describe how a completely randomized design would be implemented assuming that there are 64 plots of similar size with similar soil conditions,
(B) Describe how you would implement blocking if you had four fields in different locations and were concerned that soil conditions varied considerably.
(C) In the analysis of the results, what would the researcher wish to determine?

Answer 46

(A)There are 16 different treatments from the combination of the two fertilizers
~~Randomly assigned each treatment combination of fertilizers to four plots since 64/16=4
(B) Divide each field into 16 plots and randomly assign each treatment combination of fertilizers to the plots field so that each treatment is used four times, once in each field.
(C) The researcher would wish to see an effect of increased yield from the fertilizer.

Question 47

A study of multitasking causing increased rage is to be conducted with 40 female online teachers who have varying levels of experience.
(A) Describe how to assign experimental units to the following four treatment levels of multitasking: 0, 10, 20, and 30 task shifts per hour between answering email, grading assignments, tutoring students, answering and making phone contacts, responding to chats, and maintaining course web pages,
(B) Describe how you would implement blocking if there were 20 male and 20 female participants.
(C) Before each subject participates in the study, researchers use a survey to establish a baseline rage index. After participating in the multitasking treatment, subjects complete a survey for a new measurement of their rage index. What is this experimental design technique.
(D) If your results were inconclusive,what lurking variable could be having an effect on the outcomes?

Answer 47

(A) Randomly assign 10 subjects to each of the four treatment levels.
(B) Randomly assign five males and five females to each of the four treatment level.
(C) This is a matched-pairs design with a before and after measurement of the rage index
(D) The lurking variable could be inexperience with technology or teaching experience

Question 48

A study is conducted on female subjects to determine the effect of three types of therapy for pain: music, meditation, and exercise. The 48 females pre-screened for the study recorder pain levels of 8 or more on a scale of 0 to 10.
(A) If a leading pharmaceutical company wishes to show that its new pain medication is superior to these therapies, how would you design an experiment using the 48 female subjects?
(B) What if you suspected that there was a placebo effect associated with the new medication? What could you do?
(C) How could you control for researcher bias during this experiment?

Answer 48

(A) Randomly assign the females to one of the four treatments so there are 12 subjects in a group
(B) Make a control group that receives a placebo to measure the psychological effects of receiving a treatment
(C) Keep the treatment group of each subject hidden from the researchers who are doing pain level screenings

Question 49

A community college suspects that there is a relationship between student attendance and GPA. They select a cohort of six Introduction to Probability and Statistics classes with 50 students enrolled in each class.
(A) What observations should be made in order to determine a relationship between attendance and GPA?
(B) What type of study is this?
(C) Suppose the college believes that teachers can increase the attendance levels by doing group work that would lead to higher GPAs. How could this be tested?
(D) If the outcome is that there is no significant difference in GPA between classes receiving group work and classes receiving traditional instruction, what could explain this outcome?

Answer 49

(A) The number of absences during the semester and the grade points earned in that class
(B) Observational study
(C) The college could have half the teachers implement group work in the classes while the other half maintains traditional instruction as a control group
(D) Attendance is confounded with other variables

Question 50

Psychologists observe and document a new disorder: Attachment Deficit (AD). They wish to determine whether there is a relationship between partnering styles and the incidence of AD. They extensively interview the parents of the children displaying the disorder to construct a set of characteristics.
(A) What type of study is this?
(B) A pharmaceutical company suspects that one of its existing drugs to control psychotic episodes could be effective for AD if administered at a low dosage. Twenty parents agree to treat their AD children with the drug. What could be done if you suspect that there might be a placebo effect?

Answer 50

(A) Observational Study
(B) Divide the AD children into 2 groups. One group will receive the treatment and the other will receive a placebo.
(C) To make it double-blind, neither the subjects nor the researcher should know who is receiving the treatment or the placebo.