Business Analytics (2nd Edition)
2nd Edition
ISBN: 9780321997821
Author: James R. Evans
Publisher: PEARSON
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Textbook Question
Chapter 4, Problem 16PE
In the Excel file Facebook Survey, use a PivotTable to find the average and standard deviation of hours online/week and number of friends for females and males in the sample.
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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 4 Solutions
Business Analytics (2nd Edition)
Ch. 4 - Data obtained from a county auditor in the Excel...Ch. 4 - In the Excel file Facebook Survey, find the...Ch. 4 - For the Excel file Tablet Computer Sales, find the...Ch. 4 - Prob. 4PECh. 4 - Prob. 5PECh. 4 - Prob. 6PECh. 4 - Prob. 7PECh. 4 - Prob. 8PECh. 4 - Prob. 9PECh. 4 - Prob. 10PE
Ch. 4 - A marketing study of 800 adults in the 18—34 age...Ch. 4 - The Excel file EEO Employment Report shows the...Ch. 4 - In the Excell file Bicycle Inventory, find the...Ch. 4 - In the Sales Transactions database, find the...Ch. 4 - In the Excel file Economic Poll, find the...Ch. 4 - In the Excel file Facebook Survey, use a...Ch. 4 - In the Excel file Cell Phone Suivey, use...Ch. 4 - Using PivotTables, find the average and standard...Ch. 4 - Prob. 19PECh. 4 - Prob. 20PECh. 4 - Prob. 21PECh. 4 - Prob. 22PECh. 4 - Call centers have high turnover rates because of...Ch. 4 - In the Excel file Weddings, determine the...Ch. 4 - Prob. 25PECh. 4 - Prob. 26PECh. 4 - Prob. 27PECh. 4 - Prob. 28PECh. 4 - Prob. 29PECh. 4 - Prob. 30PECh. 4 - Prob. 31PECh. 4 - Compute the z-scores for the data in the Excel...Ch. 4 - Prob. 33PECh. 4 - Prob. 34PECh. 4 - Prob. 35PECh. 4 - Prob. 36PECh. 4 - Prob. 37PECh. 4 - Prob. 38PE
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