This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: STA 3024 Exam 3 Practice Questions 1. A simple linear regression yields the regression equation Y ( X ) = 26 . 3 . 47 X, where the X values of our data vary from about 12 to about 28. Find the predicted value of Y for a new observation with an X value of 20.8. (A) 16.5 (B) 36.1 (C) 46.6 (D) We should not predict the value of Y for this new observation, because 20.8 is between 12 and 28. 2. For n = 42 observations, we record the values of X and Y . Summary statistics for the two samples are as follows: X = 1 . 75 S X = 0 . 25 Y = 0 . 69 S Y = 0 . 16 Calculate the regression equation, Y ( X ) = a + bX . (A) Y ( X ) = . 43 + 0 . 64 X (B) Y ( X ) = 0 . 05 + 0 . 64 X (C) Y ( X ) = 1 . 81 + 0 . 64 X (D) We do not have enough information to calculate the regression equation. 3. In simple linear regression, we talk about two equations: Y ( X ) = + X and Y ( X ) = a + bX . Which one of the following statements is true? (A) is a parameter; we know its value. (B) is a statistic; we do not know its value. (C) b is a parameter; we do not know its value. (D) None of these statements are true. 4. In simple linear regression, the sample correlation between the two variables is r , and the slope of the regression line is b . Which one of the following statements is true? (A) It is possible to have a negative r and a positive b (in the same regression). (B) r depends on the units used to measure the variables, but b does not. (C) b depends on the units used to measure the variables, but r does not. (D) Both r and b depend on the units used to measure the variables. 5. Suppose we do a simple linear regression, and we use the results to do a t test for whether the X variable affects the response ( = 0 . 05). We get a pvalue of 0.011. Which one of the following statements is true? (A) We see evidence that = 0, which means we see evidence that the explanatory variable affects the response. (B) We see evidence that = 0, which means we see evidence that the explanatory variable does not affect the response. (C) We see evidence that 6 = 0, which means we see evidence that the explanatory variable affects the response. (D) None of these statements are true. 6. Were constructing the ANOVA table for a simple linear regression with 78 observations. What are df Regr and df Res ? (A) df Regr = 1 , df Res = 76 (B) df Regr = 1 , df Res = 77 (C) df Regr = 2 , df Res = 76 (D) df Regr = 2 , df Res = 77 7. In simple linear regression, which of the following would not give us enough information to calculate the total sum of squares, SS Tot ? (A) the values of SS Regr and SS Res (B) the values of a and b in the regression equation (C) the Y values of all the observations (D) the Y values of all the observations and the value of Y 8. The ANOVA table for a simple linear regression is shown below (some items are missing), along with the F test statistic value and pvalue from the regression F test....
View Full
Document
 Spring '08
 TA
 Statistics, Linear Regression

Click to edit the document details