This chapter covers the topics of data collection methods and potential sources of bias. We learned about experiments, observational studies, sample surveys and censuses. Several potential errors and sources or bias were introduced. We also learned how to use a random digit table to make random selections, how to outline experimental designs, and how to calculate and state 95% confidence intervals.
You should go back and read through each of the sections in this chapter, paying careful attention to all of the new terms in bold. This will help you to do problem 1 from your homework assignment.
Chapter 4 Review Exercises
1) Study your new vocabulary!
a) If you have not already, make flashcards for the terms from this chapter. Write the term on one side of the card. On the other side, write a brief definition and include an example. Terms that appear in bold through section 4.1 through 4.5 are the new terms.
b) Study your flashcards.
2) Each statement below claims that the ACT’s are not a fair measurement for college readiness, but for a different reason. For each student's statement, determine whether he or she is questioning the validity, the reliability, or claiming that it will be biased. Explain your answers.
a) The ACT’s are not fair because it is timed and I cannot work fast enough. Consequently I am not really doing as well as I could; I always get a lower score than I should receive.
b) The ACT’s are not fair because the vocabulary is not clear and I do not even understand what the questions are asking me. I always study really hard and do my homework and I am totally ready for college, but that doesn't show up on some stupid test.
c) The ACT’s are not fair because the first time I took them I scored a 21, but the second time I scored a 16. How can that be right?
3) Suppose you want to take a simple random sample of 350 women, from a population of 4700 females on the University of Coolness campus.
a) Explain the steps you would follow if you were going to make the selection using a table of random digits (be thorough).
b) Starting at line 137, select the first five numbers.
4) Suppose that after carrying out your survey of 350 women, you found that 74 of the women said that they “did not feel safe walking on campus after dark”. Identify each of the following.
a) Population of interest
b) Parameter of interest
e) Margin of error (quick method for 95%)
f) Calculate a 95% confidence interval
g) Make a 95% confidence statement
5) A high school social studies teacher wants to see if giving a completely multiple choice test versus a traditional free response test will improve student scores. She has designed two versions of the chapter 6 test to test her question. She has two classes – a 1st hour class with 32 students, and a 5th hour class with 37 students. The two classes are very different in both behavior and academic performance, so she decides to carry out her experiment using blocking. Identify the following:
b) Explanatory variable(s)
c) Response variable
d) Will this experiment be blind? double-blind? placebo controlled?
e) Outline a randomized block experiment.
6) Suppose that you are trying to determine whether kindergarten students who have gone to child care centers show more aggressive behaviors than children who have not attended child care centers. You have the data regarding whether or not each child attended a child care center and for what length of time. You are now going to study aggressive behaviors. For each of the following, decide which type of data collection method is being proposed: observational study, sample survey, census, or experiment.
a) Observers will watch the kindergartners on the playground, recording aggressive behaviors.
b) A survey will be given to 20 randomly selected parents asking each to rate his or her child’s behavior.
c) A survey will be given to all kindergarten parents asking each to rate his or her child’s behavior.
d) During center time, a teacher will take a toy away from a child and record whether they act aggressively.
7) For the study in question 6
a) Suggest something that may go wrong with, or may be a source of bias, for each of the proposed data collection methods.
b) Which of the methods do you feel will yield the best results? Explain.
8) A researcher at the University of Minnesota believes that a certain component of ant venom can be used to lessen the amount of swelling in the knuckles of people suffering from arthritis. The ant venom treatment has been made into a capsule form that can be swallowed, and is designed to be taken one time per day. Suppose that you have 200 people suffering from arthritis who have volunteered to participate in this study. Identify the following:
b) Explanatory variable
c) Response variable
d) Will this experiment be blind? double-blind? placebo controlled?
e) Outline a completely randomized design
9) Your teacher wants to find out whether chocolate helps students concentrate on their tests. In one class, she gives all of the students chocolate before the test begins. In another class, she does nothing. Is this an example of an observational study, a sample survey, a census, or an experiment? Give reasons to support your answer.
10) You bought a sweater on discount that was originally marked at $30. When you got to the register, it rung up as $23. What was the percent discount?
11) The cost of gas in 2001 was $1.45 per gallon. The average cost today is $3.75.
a) What is the amount of increase?
b) What is the percent of increase?
12) The table below shows the number of seniors and the number of seniors graduating for three high schools.
a) Which school has the most students graduating?
b) Determine the graduation rate for each school.
c) Which school has the highest graduation rate?
13) Identify the sampling method used in each of the following: SRS, stratified random sample, systematic random sample, multi-stage random sample, random cluster sample, voluntary response sample, convenience sample
a) Every fifth person boarding a plane is searched thoroughly.
b) At a local community College, five math classes are randomly selected out of 20 and all of the students from each class are interviewed.
c) A researcher randomly selects and interviews forty male and forty female teachers, from a university with 122 female and 135 male instructors.
d) A researcher for an airline interviews all of the passengers on five randomly selected flights.
e) Based on 12,500 responses from 42,000 surveys sent to its alumni, a major university estimated that the annual salary of its alumni was 92,500.
f) A community college student interviews everyone in his biology class to determine the percentage of students that own a car.
g) A market researcher randomly selects 200 drivers under 35 years of age and 100 drivers over 35 years of age, from those insured with Quality Car Insurance.
h) A researcher selects 12 states randomly. From each state, she randomly selects 20 middle schools. From each middle schools, she randomly selects 15 teachers. The 3,600 teachers were then interviewed by phone..
i) To avoid working late, the quality control manager inspects the last 10 items produced that day.
j) The names of 70 contestants are written on 70 cards. The cards are placed in a bag, and three names are picked from the bag.
14) The athletic director wants to know how tax payers in the community feel about funding for athletics at the high school. He surveys his coaches and the parents of athletes at his school. Describe what is wrong with his methodology.
15) Suppose that a poll was commissioned to determine whether people in the U.S. believe that pro wrestling is a sport. Identify the type(s) of bias that will likely be present in each of the following scenarios. Some will have more than one. Explain your answers.
a) An online poll was sent to all visitors of the WWE website.
b) Telephone interviews are done to randomly selected phone numbers between 4 p.m. and 8 p.m.
c) Some people were embarrassed to admit that they liked wrestling and think it is a sport.
d) One of the questions asked was, “Do you believe that the pro wrestlers are actors or should they be considered serious athletes?”
e) One of the researchers spilled coffee on a big stack of surveys and several had to be thrown away.
f) A second poll done had slightly different results.
g) WWE had fans fill out a survey as they left a pro wrestling event.
Picture of cell phones. http://www.w-cellphones.com July 19, 2011.
Students measuring heights.http://t3.gstatic.com July 25, 2011.
Pop can. http://popartmachine.com July 25, 2011.
Calvin and Hobbes. http://www.stat.psu.edu/old_resources/Cartoons/cartoon014.gif July 27, 2011.
Clipboard. http://boylston.bbrsd.schoolfusion.us July 25, 2011.
Hockey Players.http://images.paraorkut.com July 25, 2011.
Scientist:http://www.reversingibs.com July 15, 2011.