MATH 534 Week 6 Quiz

1. Question: A value of -1 for the coefficient of correlation between two variables means that the two variables are _____________. 2. Question: If there is positive correlation between two sets of numbers, then ____________-. 3. Question: If the correlation coefficient between variables X and Y is roughly zero, then ___________. 4. Question: Determine the Pearson product-moment correlation coefficient for the following data. 5. Question: A quality manager is developing a regression model to predict the total number of defects as a function of the day of week the item is produced. Production runs are done 10 hours a day, 7 days a week. The dependent variable is _____________-. 6. Question: In the equation y = m x + b, which represents a straight lime, b is the _____________. 7. Question: If the relationship between y and x is given by the equation y = 1.57 — 0.0407 x, the slope coefficient 0.0407 means this: _________. 8. Question: Least squares regression line is one that ______________. 9. Question: The following regression model was fitted to sample data with 12 observations: y = 30 + 4.50x. What is the predicted value of y for a given value of x = 6? 10. Question: For a least squares regression line, the sum of the residuals is ___________. 11. Question: If the standard error of the estimate for a regression model fitted to a large number of paired observations is 1.75, approximately 95% of the residuals would lie within ___________. 12. Question: If x and y in a regression model are totally unrelated, _________. 13. Question: Suppose we are making predictions of the dependent variable y for specific values of the independent variable x using a simple linear regression model holding the confidence level constant. Let Width (C.I) = the width of the confidence interval for the average value y for a given value of x, and Width (P.I) = the width of the prediction interval for a single value y for a given value of x. Which of the following statements is true? 14. Question: In the regression equation, y = 2.164 + 1.3657x, n = 6, the mean of x is 8.667, SSxx= 89.333 and Se = 3.44. A 95% confidence interval for the average of y when x = 8 is _____________. 15. Question: A manager wishes to predict the annual cost (y) of an automobile based on the number of miles (x) driven. The following model was developed: y = 2,000 + 0.42x. If a car is driven 30,000 miles, the predicted cost is ________. 16. Question: A manager wants to predict the cost (y) of travel for salespeople based on the number of days (x) spent on each sales trip. The following model has been developed: y = $400 + 120x. If a trip took 4 days, the predicted cost of the trip is ___________.