Chapter 5 Review

The Mayor of Port Orange wants to know what the residents think of a proposed policy to change the billing of utilities in the area. His staff reports that 300 letters have been received on the matter, of which 219 oppose changing the current billing method. What is the population in this situation? The Mayor of Port Orange wants to know what the residents think of a proposed policy to change the billing of utilities in the area. His staff reports that 300 letters have been received on the matter, of which 219 oppose changing the current billing method. What is the population in this situation? A. 300 letters received B. 219 opposing the change in the billing method C. The residents

What do we call a sample that consists of the entire population? What do we call a sample that consists of the entire population? A. A census B. A stratum C. A big mistake

Which of the following is a method for improving the accuracy of a sample? Which of the following is a method for improving the accuracy of a sample? A. Use smaller sample sizes B. Use no more than 5 or 6 words in any question. C. Use computerized dialing whenever possible to avoid human interviewers. D. Use large sample sizes.

A design is biased if which of the following is true? A design is biased if which of the following is true? A. Placebos have been used. B. Systematic favoritism in outcomes. C. A sexual or racial preference is suspected.

Why are control groups used in experiments? Why are control groups used in experiments? A. To ensure all participate equally. B. To guarantee others than the investigators, who have a vested interest in the outcome, control how the experiment is conducted. C. To minimize the effects of lurking variables i.e. placebo effect.

Suppose the NewsJournal asks a sample of 250 Volusians their opinion on property taxes in Volusia County. Is this study an experiment? Why or why not? No. A treatment isn’t imposed Is this study an experiment? Why or why not? No. A treatment isn’t imposed What is the sample for this opinion poll? 250 Volusians What is the sample for this opinion poll? 250 Volusians What is the population? All Volusians What is the population? All Volusians

Vitamin E may have special health benefits Large doses of vitamin E apparently can reduce harmful side effects of bypass surgery in heart patients. A study involving 28 bypass patients found that the 14 patients who took vitamin E for two weeks before their operations had significantly better heart function after the procedure than the 14 patients who took placebos. The vitamins apparently prevent damage to the heart muscle by destroying the toxic chemicals, called free radicals, that form when blood is cut off during the surgery, said Dr. Terrance Yau of the University of Toronto.

Does the article on Vitamin E describe an experiment? Explain. Yes, treatment imposed. Does the article on Vitamin E describe an experiment? Explain. Yes, treatment imposed. Describe the experimental units/subjects used. How many were there? 28 bypass patients Describe the experimental units/subjects used. How many were there? 28 bypass patients Identify the explanatory variable (s). Medication given Identify the explanatory variable (s). Medication given How many treatments were there? List them. 2 – Vitamin E and a placebo How many treatments were there? List them. 2 – Vitamin E and a placebo How many participants are in each treatment group? 14 How many participants are in each treatment group? 14 Identify the response variable. Heart function (better) after the procedure. Identify the response variable. Heart function (better) after the procedure.

Using line 125 of your Random Numbers Table (RNT), select the first five students in a simple random sample (SRS) of 20 students. Alphabetize the 500 students and assign the numbers ignoring 500 – 999 in my RNT. 461, 214, 235, 119, 033 Suppose there are 500 students in the Senior Class of 2007

Bias is present in each of the following sampling designs. In each case, identify the type of bias involved and state whether you think the sampling frequency obtained is lower or higher than the actual population parameter. Types of Biases - Undercoverage – Groups are left out - Nonresponse – chosen and cannot be reached/refuses to cooperate - Wording of questions – too technical/filled with jargon

A pollster seeks information about the proportion of American adults that oppose gun controls. He asks a SRS of 100 American adults: “Do you agree or disagree with the following statement: Americans should preserve their constitutional right to keep and bear arms.” A total of 91 or 91%, said, “agree”. Wording of Question. Sampling is higher than the population parameter.

A chocolate company in Hershey wants to know what percentage of local households make chocolate chip cookies at least twice a week. A company representative calls 500 households during the daytime and finds that 50% of them make cookies at least twice a week. Nonresponse – households have been chosen, but some folks are working. Sampling parameter is higher than the population parameter.

It is believed that 80% of all students use their lockers daily. Describe how you would simulate a SRS of 10 students. To simulate the 80% which would constitute a success, I would assign the numbers 0 – 7 for using their locker, l. Assign 8 and 9 for non use of locker (failure), n. Beginning at line 127, I would select one digit at a time until I get 10 digits which would represent the 10 students. I would record my findings and then compare. Describe how you would simulate a SRS of 10 students. To simulate the 80% which would constitute a success, I would assign the numbers 0 – 7 for using their locker, l. Assign 8 and 9 for non use of locker (failure), n. Beginning at line 127, I would select one digit at a time until I get 10 digits which would represent the 10 students. I would record my findings and then compare. Beginning at line 127, actually simulate a SRS of 10 students. Beginning at line 127, actually simulate a SRS of 10 students. 4, 3, 9, 0, 9, 9, 9, 4, 7, 7 4, 3, 9, 0, 9, 9, 9, 4, 7, 7 l, l, n, l, n, n, n, l. l. l Use locker – 6; non use of locker 4 l, l, n, l, n, n, n, l. l. l Use locker – 6; non use of locker 4 What is the proportion of students in the sample who use their lockers daily? What is the proportion of students in the sample who use their lockers daily? 6/10 = 60% 6/10 = 60%

Turkeys raised commercially for food are often fed the antibiotic salinomycin to prevent infections from spreading among the birds. However, salinomycin can damage the birds' internal organs, especially the pancreas. A researcher believes that a combination of selenium and vitamin E in the birds' diet may prevent injury. He wants to explore the effects of two different dosages of selenium (call them S1, S2) in combination with any of three different dosages of vitamin E (call them E1, E2, E3) added to the turkeys' diets. There are 48 turkeys available for the study. At the end of the study, the birds will be killed and the condition of their pancreas examined with a microscope.

Outline in diagram form an appropriate design for this experiment. In your diagram, indicate how many turkeys are assigned to each treatment group. Discuss how you would assign the turkeys to the first treatment group. Random Assignment 01 – 48 (The ABCs aren’t necessary) Treatment 1 S1E1 8 turkeys Treatment 1 S1E2 8 turkeys Treatment 3 S1E3 8 turkeys Treatment 4 S2E1 8 turkeys Treatment 5 S2E2 8 turkeys Treatment 6 S2E3 8 turkeys Compare Examine the turkeys before diet change. First 8 turkeys will be assigned to group 1, the 2 nd set of 8 to group 2, and etc until all turkeys are placed in a group. After a period of time the turkeys will be killed and their pancreas examined.

Chapter 5 Test Good luck on the test