UNDERSTANDABLE STAT. >PRINT UPGRADE<
12th Edition
ISBN: 9780357724880
Author: BRASE
Publisher: CENGAGE L
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Textbook Question
Chapter 1.3, Problem 9P
General: Completely Randomized Experiment How would you use a completely randomized experiment in each of the following settings? Is a placebo being used or not? Be specific and give details.
- (a) A veterinarian wants to test a strain of antibiotic on calves to determine their resistance to common infection. In a pasture are 22 newborn calves. There is enough vaccine for 10 calves. However, blood tests to determine resistance to infection can be done on all calves.
- (b) The Denver Police Department wants to improve its image with teenagers. A uniformed officer is sent to a school 1 day a week for 10 weeks. Each day the officer visits with students, eats lunch with students, attends pep rallies, and so on. There are 18 schools, but the police department can visit only half of these schools this semester. A survey regarding how teenagers view police is sent to all 18 schools at the end of the semester.
- (c) A skin patch contains a new drug to help people quit smoking. A group of 75 cigarette smokers have volunteered as subjects to test the new skin patch. For 1 month, 40 of the volunteers receive skin patches with the new drug. The other volunteers receive skin patches with no drugs. At the end of 2 months, each subject is surveyed regarding his or her current smoking habits.
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3. Bayesian Inference – Updating Beliefs
A medical test for a rare disease has the following characteristics:
Sensitivity (true positive rate): 99%
Specificity (true negative rate): 98%
The disease occurs in 0.5% of the population.
A patient receives a positive test result.
Questions:
a) Define the relevant events and use Bayes’ Theorem to compute the probability that the patient actually has the disease.b) Explain why the result might seem counterintuitive, despite the high sensitivity and specificity.c) Discuss how prior probabilities influence posterior beliefs in Bayesian inference.d) Suppose a second, independent test with the same accuracy is conducted and is also positive. Update the probability that the patient has the disease.
4. Linear Regression - Model Assumptions and Interpretation
A real estate analyst is studying how house prices (Y) are related to house size in square feet (X). A simple
linear regression model is proposed:
The analyst fits the model and obtains:
•
Ŷ50,000+150X
YBoB₁X + €
•
R² = 0.76
• Residuals show a fan-shaped pattern when plotted against fitted values.
Questions:
a) Interpret the slope coefficient in context.
b) Explain what the R² value tells us about the model's performance.
c) Based on the residual pattern, what regression assumption is likely violated? What might be the
consequence?
d) Suggest at least two remedies to improve the model, based on the residual analysis.
Chapter 1 Solutions
UNDERSTANDABLE STAT. >PRINT UPGRADE<
Ch. 1.1 - Statistical Literacy In a statistical study what...Ch. 1.1 - Statistical Literacy Are data at the nominal level...Ch. 1.1 - Statistical Literacy What is the difference...Ch. 1.1 - Statistical Literacy For a set population, does a...Ch. 1.1 - Critical Thinking Numbers are often assigned to...Ch. 1.1 - Interpretation Lucy conducted a survey asking some...Ch. 1.1 - Marketing: Fast Food A national survey asked 1261...Ch. 1.1 - Advertising: Auto Mileage What is the average...Ch. 1.1 - Ecology: Wetlands Government agencies carefully...Ch. 1.1 - Archaeology: Ireland The archaeological site of...
Ch. 1.1 - Student Life: Levels of Measurement Categorize...Ch. 1.1 - Business: Levels of Measurement Categorize these...Ch. 1.1 - Fishing: Levels of Measurement Categorize these...Ch. 1.1 - Education: Teacher Evaluation If you were going to...Ch. 1.1 - Critical Thinking You are interested in the...Ch. 1.2 - Statistical Literacy Explain the difference...Ch. 1.2 - Statistical Literacy Explain the difference...Ch. 1.2 - Statistical Literacy Marcie conducted a study of...Ch. 1.2 - Statistical Literacy A random sample of students...Ch. 1.2 - Interpretation In a random sample of 50 students...Ch. 1.2 - Interpretation A campus performance series...Ch. 1.2 - Critical Thinking Greg took a random sample of...Ch. 1.2 - Critical Thinking Consider the students in your...Ch. 1.2 - Critical Thinking Suppose you are assigned the...Ch. 1.2 - Critical Thinking In each of the following...Ch. 1.2 - Sampling: Random Use a random-number table to...Ch. 1.2 - Prob. 12PCh. 1.2 - Sampling: Random Use a random-number table to...Ch. 1.2 - Prob. 14PCh. 1.2 - Computer Simulation: Roll of a Die A die is a cube...Ch. 1.2 - Education: Test Construction Professor Gill is...Ch. 1.2 - Education: Test Construction Professor Gill uses...Ch. 1.2 - Sampling Methods: Benefits Package An important...Ch. 1.2 - Sampling Methods: Health Care Modern Managed...Ch. 1.3 - Statistical Literacy A study of college graduates...Ch. 1.3 - Statistical Literacy Consider a completely...Ch. 1.3 - Critical Thinking A brief survey regarding...Ch. 1.3 - Critical Thinking A randomized block design was...Ch. 1.3 - Interpretation Zane is examining two studies...Ch. 1.3 - Interpretation Suppose you are looking at the 2006...Ch. 1.3 - Ecology: Gathering Data Which technique for...Ch. 1.3 - General: Gathering Data Which technique for...Ch. 1.3 - General: Completely Randomized Experiment How...Ch. 1.3 - Surveys: Manipulation The New York Times did a...Ch. 1.3 - Critical Thinking An agricultural study is...Ch. 1 - Critical Thinking Sudoku is a puzzle consisting of...Ch. 1 - Prob. 2CRPCh. 1 - Statistical Literacy You are conducting a study of...Ch. 1 - Prob. 4CRPCh. 1 - Prob. 5CRPCh. 1 - General: Type of Sampling Categorize the type of...Ch. 1 - Prob. 7CRPCh. 1 - General: Experiment How would you use a completely...Ch. 1 - Prob. 11CRPCh. 1 - Prob. 2DHCh. 1 - Prob. 1LCCh. 1 - Discuss each of the following topics in class or...Ch. 1 - Prob. 1UTCh. 1 - Prob. 2UT
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