MATH 534 Week 6 Addendum; Homework-Quiz Review

1. Question: You can skip #16 in the homework and #9 and #10 in the quiz. Everyone will be given credit. The problems look something like this: 2. Question: Review definitions and concepts in the notes. 3. Question: We are developing a regression model to predict weight as function of height. a. What is the explanatory variable (independent variable)? b. What is the response variable (dependent variable)? 4. Question: In the following regression: ŷ = 27.7 + 3.25x a. What is the slope? b. What is the y-intercept? 5. Question: Use the following data to construct a regression model: 6. Question: For the following scatter plot and regressionline, at x=26, isthe residual negative, positive or zero? 7. Question: If the coefficient of determination (r-squared) is.81, what is the correlation coefficient (r)? 8. Question: If the coefficient of correlation is -0.9, what isthe coefficient of determination? 9. Question: We want to predict weight (y) based on height (x). The following equation shows the relationship: ŷ = 70 + 1.3x. If someone is 65 inches tall, what would the predicted weight be? 10. Question: In the equation ŷ = 70 + 1.3x, what is the x-intercept? 11. Question: True/False. A regression line minimizes the sum of squared errors. This means that the regression line minimizes the sum of from each point in the scatter plot to the regression line. 12. Question: Suppose for a given data set the regression equation is: y = 50 + 3x, and the point (2.2, 58) is in the data set. The residual for this point is _________-. 13. Question: Hypothesistestsfor individual regression coefficients (i.e. B0, B1) model use t-tests. 14. Question: Hypothesistests for the entire regression model use F-tests. 15. Question: Skip #16 on the quiz. It appears that not enough information is given. The problems looks like this: 16. Question: Eight children ran a 100-yard dash and were timed. Below are their ages and times. a. What type of correlation exists for this data? b. What is the 90% confidence interval for children who are 12 years old? c. What is the 90% prediction interval for someone who is 12 years old? 17. Question: True/False. A plot of the residuals should show a constant variance. Answer: True Explanation: When you plot the residuals, they must have uniform (constant) variance as shown in the third graph below. They should not have a non-constant variance, as shown in the in the first two graphs below. 18. Question: We want to study the correlation between height of corn plants and amount of rain. Our independent variable is amount of rain (in inches) and the dependent variable is the height of a corn plant. We run regression analysis and get the following table from the software we are using: a. What is the regression model? b. What is the coefficient of determination? c. Using Alpha = .10, should we reject Ho: Bo = 0 d. Using Alpha = .10, should we reject Ho: B1 = 0