EBK UNDERSTANDING BASIC STATISTICS
7th Edition
ISBN: 8220100547560
Author: BRASE
Publisher: CENGAGE L
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Chapter 1.2, Problem 6P
Interpretation A campus performance series features plays, music groups, dance troops, and stand-up comedy. The committee responsible for selecting the performance groups includes three students chosen at random from a pool of volunteers. This year, the 30 volunteers came from a variety of majors. However, the three students for the committee were all music majors. Does this fact indicate there was bias in the selection process and that the selection process was not random? Explain.
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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.
5. Probability Distributions – Continuous Random Variables
A factory machine produces metal rods whose lengths (in cm) follow a continuous uniform distribution on the interval [98, 102].
Questions:
a) Define the probability density function (PDF) of the rod length.b) Calculate the probability that a randomly selected rod is shorter than 99 cm.c) Determine the expected value and variance of rod lengths.d) If a sample of 25 rods is selected, what is the probability that their average length is between 99.5 cm and 100.5 cm? Justify your answer using the appropriate distribution.
Chapter 1 Solutions
EBK UNDERSTANDING BASIC STATISTICS
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 - Sampling: Random Use a random-number table to...Ch. 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 - Prob. 16PCh. 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 - Prob. 1PCh. 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 - Prob. 6PCh. 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 - Survey: Manipulation The NewYork Times did a...Ch. 1.3 - Critical Thinking An agricultural study is...Ch. 1 - Critical Thinking Sudoku is a puzzle consisting of...Ch. 1 - Critical Thinking Alisha wants to do a statistical...Ch. 1 - Statistical Literacy You are conducting a study of...Ch. 1 - Radio Talk Show: Sample Bias A radio talk show...Ch. 1 - Prob. 5CRCh. 1 - General: Type of Sampling Categorize the type of...Ch. 1 - General: Gathering Data Which technique fur...Ch. 1 - General: Experiment How would you use a completely...Ch. 1 - Student Life: Data Collection Project Make a...Ch. 1 - Form Problem: Fireflies Suppose you air conducting...Ch. 1 - Prob. 1DHGPCh. 1 - Use a random-number table or random-number...Ch. 1 - What does it mean to say that we are going to use...Ch. 1 - In your own words, explain the differences among...Ch. 1 - Simulate the results of tossing a fair die 18...Ch. 1 - Prob. 2UTA
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