Chapter 4 Experiments And Studies Take Home Practice Test

AP Statistics Take Home PRACTICE TEST Chapter 4

Name:______

Date:______Period:______Chapter 4: Take Home Practice Test Part 1: Multiple Choice. (2 points each) Hand write the letter corresponding to the best answer in space provided on page 6.

_____1. Which one of the following is not a principle of experimentation?

(a) Randomly allocating experimental units to treatments. (b) Stratifying the experimental units into groups of similar individuals and applying different treatments to each stratum. (c) Using double blindness to eliminate bias. (d) Replicating to measure overall experimental error and increase precision. (e) Using a control group to determine whether treatment really works.

_____2. In sample surveys, bias can be controlled by all of the following except

(a) Using a probability or chance sampling procedure. (b) Wording questions so they are not confusing or misleading. (c) Carefully training and supervising interviewers. (d) Prompting respondents so that they give correct responses. (e) Reducing non-response and undercoverage.

_____3. In a study on the effect of reinforcement on learning from programmed text, two experimental treatments are planned: reinforcement given after every frame of programmed text or reinforcement given after every three frames. Which one of the following control groups would serve best in this study? (a) A group which does not read the programmed text material. (b) A group that reads the programmed material in prose formats. (c) A group which reads the programmed material but does not receive reinforcement. (d) A group that reads the programmed text material and reinforcement is given at random. (e) A group which watches the video of the programmed material.

______4. A graduate student did a study to determine whether a new activity-based method is better than the traditional lecture of teaching statistics. He found two teachers to help him in his study for one semester. Mr. Dull volunteered to continue teaching with traditional lectures and Ms. Perky agreed to try the new activity-based method. Each teacher planned to teach two sections of approximately forty students each for adequate replication. At the end of the semester, all sections would take the same final exam and their scores would be compared. What is the treatment variable in this study? (a) Teacher (b) Section of the Course (c) Teaching Method (d) Final Exam Score (e) Student

Mr. Page Chapter 4 page 1 AP Statistics Take Home PRACTICE TEST Chapter 4

_____5. Which of the following are true statements? I. Voluntary response samples often under-represent people with strong opinions. II. Convenience samples often lead to undercoverage bias. III. Questionnaires with non-neutral wording are likely to have response bias.

(a) I and II (b) I and III (c) II and III (d) I, II, and III (e) None of the above gives the true set of responses.

_____ 6. What fault do all these sampling designs have in common? I. The Wall Street Journal plans to make a prediction for a presidential election based on a survey of its readers. II. A radio talk show asks people to phone in their views on whether the United States should pay off its huge debt to the United Nations. III. A police detective interested in determining a sample of high school students and interviews each one about any illegal drug use by the student during the past year.

(a) All the designs make improper use of stratification. (b) All the designs have errors that can lead to strong bias. (c) All the designs confuse association with cause and effect. (d) None of the designs satisfactorily controls for sampling error. (e) None of the designs makes use of chance in selecting a sample.

_____7. To survey the opinions of bleacher fans at Wrigley Field, a surveyor plans to select every one- hundredth fan entering the bleachers one afternoon. Will this result in a random sample?

(a) Yes, because each bleacher fan has the same chance of being selected. (b) Yes, but only if there is a single entrance to the bleachers. (c) Yes, because the 99 out of 100 bleacher fans that are not selected will form a control group. (d) Yes, because this is an example of systematic sampling, which is a special case of random sampling. (e) No, because a random start was not specified.

_____8. A researcher wishes to determine if watching 4 or more hours of TV per day adversely affects high school students’ academic performance. Which of the following designs is best?

(a) Study the records of randomly selected students (b) Interview randomly selected students on their grades and TV habits (c) Monitor the grades and TV habits of randomly selected students (d) Monitor the grades of students randomly placed into an under four-hour TV group and an over four-hour TV group (e) Monitor the grades of students randomly placed into an under four-hour TV group, an over four- hour TV group and a no TV group Mr. Page Chapter 4 page 2 AP Statistics Take Home PRACTICE TEST Chapter 4

Use the following information to answer questions # 9-11 A personnel director at a large company studied the eating habits of employees by watching the movement of a selected group of employees at lunchtime. The purpose of the study was to determine the proportion of employees who buy lunch in the cafeteria, bring their own lunches, or go out to lunch

_____9. The study would best be categorized as: (a) A census (b) A survey sample (c) An observational study (d) A designed experiment (e) None of these

_____10. If the director includes only the employees in one department in her study, she is performing a (a) Simple random sample (b) Quota sample (c) Convenience sample (d) Multi-stage random sample (e) Census

_____11. If the director selects 50 employees at random throughout the company and categorizes their lunchtime practices by gender, she is: (a) Blocking for gender (b) Testing for a lurking variable (c) Promoting sexual harassment (d) Testing for bias (e) None of these

_____12. Which of the following is not a valid sample design?

(a) Code every member of a population and select 100 randomly chosen members (b) Divide a population by gender and select 50 individuals from each group (c) Select individuals randomly and place into gender groups until you have the same proportion in the groups as in the population (d) Select five homerooms at random from all of the homerooms in a large high school (e) All of these are valid ______Use the following excerpt from the random digit table to answer questions 15-17 21052 65031 45074 92846 67815 78231 01548 20235 56410 82713

_____13. Which of the following statements regarding this excerpt of given random digits is true?

(a) The table can only be used for data coded with five-digit numbers. (b) In order to use this table for a population of 100 names, the names could be coded 00 to 99; then distinct two-digit numbers would be selected sequentially to identify chosen names. Mr. Page Chapter 4 page 3 AP Statistics Take Home PRACTICE TEST Chapter 4

(c) It is critical to begin the selection of random digits at the beginning of the list. (d) This table can only be used if the data labels include all of the digits in the table. (e) None of these statements is true.

_____14. You have been given the task of determining if right-handed persons have stronger right hands than left hands. A sample of 10 right-handed persons is selected randomly. Which of the following designs would be most appropriate for this study?

(a) An observational study (b) A design blocked for gender to determine if right-hand strength differs by gender (c) A matched pair study in which each subject represents a block wherein the strength of the right hand and the left hand is measured in random order (d) Five of the subjects and randomly placed in the control group and the other in the treatment group. All are tested and the results of each group are compared (e) None of these is appropriate

_____15. Which of the following is an example of a census?

(a) Every fifth person leaving a supermarket is asked to name his or her favorite brand of peanut butter. (b) Each employee in a corporation fills out a questionnaire for a management survey. (c) All the students (who are at school a particular day) rate the food in the cafeteria. (d) A telephone political poll selects ten names form every page of a city directory. (e) All the commuters who are dissatisfied with the service of their commuter train company are asked to write a letter of complaint.

Name:______

Date:______Period:______PART I answers (2 points each) 1. 2. 3. 4. 5.

6. 7. 8. 9 10.

11. 12. 13. 14. 15.

PART II - Answer completely, but be concise. Write sequentially and show all steps. Show all your work. Indicate clearly the methods you used, because you will be graded on the correctness of your methods as well as on the accuracy of your results and explanations. YOU MUST WRITE ANSWERS IN BY HAND – you need not print out the first 4 pages.

1. In competitive sports, video recorders have been used more frequently in recent years. The idea behind the recorder is that coaches can replay training sessions for more effective feedback to the athlete. Some people believe video recording may make the athletes more nervous and actually decrease their performance. You have been asked to design an experiment to address this issue for competitive high school tennis players. You have decided to use the accuracy of tennis serves as your response variable, and the number of successful serves out of 100 as your performance measure. The subjects for your experiment are 60 high school male competitive tennis players of varying ability who have volunteered for the experiment. a) Describe the treatments in your experiment. (4 points)

b) One possible confounding variable is the experience levels of the players. Explain how you would control this variable? (4 points)

2. One of the tasks of wildlife biologists is to estimate bird populations. One method for doing this is to walk a “transect,” typically a long randomly selected rectangle, and count the number of particular species that are seen. During hunting season the biologists wear brightly colored clothes as a protective measure. A theory, known as the “species-confidence hypothesis,” predicts that birds may react to these brightly colored clothes. A robin, for example, when confronted with a biologist wearing an orange color may be less afraid than if the biologist were wearing a brown color. The idea is that the orange color gives the robin some “confidence” that the biologist is another (really big!) bird. This is a difficulty because a robin that is less afraid of the biologist may be easier to see and therefore “count” because the robin lets the biologist get closer. This would result in too high an estimate of the robin population. To test this theory a biologist performed a study in her area, wearing a bright orange vest or a brown vest while working. After training herself to accurately estimate distances she indicated on her notes how close the robins would let her get before they flew away (the “approach distance”), using this as a measure of their “confidence.” She randomly selected her starting points in each trip through the transects and also carefully noted the weather conditions, specifically the wind speed. (a) What is the explanatory variable (factor) for this experiment? (4 points)

(b) What is the response variable for this experiment? (4 points)

(c) After completing the study the biologist was examining her results and noticed that on those days she wore the brightly-colored vest the wind tended to be of greater velocity. How does this information affect the interpretation of the results of the experiment? (4 points)

3. The following paragraph describes an actual study. After reading the description, determine whether the study is an observational study or an experiment. Justify your answer with specific references to the information in the study. (6 points)

"We compared paired daytime and night counts of wild brook trout, brown trout, and rainbow trout made by the same snorkelers in five streams during August 1994. Overall, we counted 109 trout in the daytime and 333 trout at night. We speculate that trout counted at night were present during the daytime but were hidden from view. Biologists should consider that trout behavior and susceptibility to being seen might vary a great deal between daytime and night, even during summer. In some streams, the majority of trout may not be seen during the daytime."

4. When a tractor pulls a plow through an agricultural field, the energy needed to pull that plow is called the draft. The draft is affected by environmental conditions such as soil type, terrain, and moisture. A study was conducted to determine whether a newly developed hitch would be able to reduce draft compared to the standard hitch. (A hitch is used to connect the plow to the tractor). Two large plots of land were used in this study. It was randomly determined which plot was to be plowed using the standard hitch. As the tractor plowed that plot, a measurement device on the tractor automatically recorded the draft at 25 randomly selected points in the plot. After the plot was plowed, the hitch was changed from the standard one to the new one, a process that takes a substantial amount of time. Then the second plot was plowed using the new hitch. Twenty-five measurements of draft were also recorded at randomly selected points in this point. (12 points)

(a) What was the response variable in this study? Identify the treatments. What is the experimental units?

(b) Given that the goal of the study is to determine whether a newly developed hitch reduced draft compared to the standard hitch, was randomization used properly in this study? Justify your answer.

(c) Given that the goal of the study is to determine whether a newly developed hitch reduced draft compared to the standard hitch, was replication used properly in this study? Justify your answer.

(d) Plot of land is a confounding variable in this experiment. Explain why. Mr. Page Chapter 4 page 7 AP Statistics Take Home PRACTICE TEST Chapter 4

5. At the recently opened theme park, Six Samples Over a Population, a carnival game allows a player three attempts, using a dart, to pop a balloon. As soon as the player pops the balloon, he wins the prize and the game is over. If he does not pop the balloon after the third attempt he loses. Shenyan, an avid dart-throwing balloon popper, estimates his probability of popping the balloon on the first attempt at 20%, popping the balloon on the second attempt at 30%, and popping the balloon on the third attempt at 40%. By describing an appropriate random digit assignment and performing 10 simulations using the given random number table, determine the probability that Shenyan wins the prize. (12 points)

0 8 4 2 4 4 4 7 5 3 7 7 3 7 7 2 8 7 4 4 7 5 5 9 2 0 8 5 6 3 7 9 1 4 0 9 2 4 5 4 5 3 6 4 5 6 6 8 1 2 6 1 4 2 1 4 7 8 3 6 1 2 6 0 9 1 5 3 7 3 9 8 4 8 1 1 4 5 9 2

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