1 It is believed that, the average numbers of hours spent studying per day (HOUR
ID: 3151996 • Letter: 1
Question
1 It is believed that, the average numbers of hours spent studying per day (HOURS) during undergraduate education should have a positive linear relationship with the starting salary (SALARY, measured in thousands of dollars per month) after graduation. Given below is the Excel output for predicting starting salary (Y) using number of hours spent studying per day (X) for a sample of 51 students. NOTE: Only partial output is shown.
Note: 2.051E - 05 = 2.051 ? 10-05 and 5.944E - 18 = 5.944 ? 10-18.
Referring to Table 13-9, the estimated change in mean salary (in thousands of dollars) as a result of spending an extra hour per day studying is
A. 335.0473.
B. 0.9795.
C. 0.7845.
D. -1.8940.
2 The sample correlation coefficient between X and Y is 0.375. It has been found out that the p-value is 0.256 when testing H0 : ? = 0 against the two-sided alternative H1 : ? ? 0. To test H0 : ? = 0 against the one-sided alternative H1 : ? > 0 at a significance level of 0.1, the p-value is
A. 0.256 / 2.
B. (0.256) 2.
C. 1 - 0.256.
D. 1 - 0.256 / 2.
3 The following Excel tables are obtained when "Score received on an exam (measured in percentage points)" (Y) is regressed on "percentage attendance" (X) for 22 students in a Statistics for Business and Economics course.
Referring to Table 13-6, which of the following statements is true?
A. 14.26% of the total variability in score received can be explained by percentage attendance.
B. 2% of the total variability in percentage attendance can be explained by score received.
C. 14.2% of the total variability in percentage attendance can be explained by score received.
D. 2% of the total variability in score received can be explained by percentage attendance.
4 Which of the following assumptions concerning the probability distribution of the random error term is stated incorrectly?
A. The errors are independent.
B. The mean of the distribution is 0.
C. The variance of the distribution increases as X increases.
D. The distribution is normal.
5 The sample correlation coefficient between X and Y is 0.375. It has been found out that the p-value is 0.744 when testing H0 : ? = 0 against the one-sided alternative H1 : ? < 0. To test H0 : ? = 0 against the two-sided alternative H1 : ? ? 0 at a significance level of 0.1, the p-value is
A. 1 - 0.744.
B. (0.744)(2).
C. 0.744 / 2.
D. (1 - 0.744)(2).
6 True or False: The confidence interval for the mean of Y is always narrower than the prediction interval for an individual response Y given the same data set, X value, and confidence level
A. True
B. False
7 True or False: Data that exhibit an autocorrelation effect violate the regression assumption of independence
A. True
B. False
8 True or False: The Regression Sum of Squares (SSR) can never be greater than the Total Sum of Squares (SST).
A. True
B. False
A. 335.0473.
B. 0.9795.
C. 0.7845.
D. -1.8940.
Explanation / Answer
1) 0.9795, since the coefficient of hours is 0.9795
2) it is p/2 = 0.256/2
3) 2% of the total variability in score received can be explained by percentage attendance.
4) The variance of the distribution increases as X increases.
5) 1- p/2 = 1-0.744/2
6) true
7) true
8) SST = SSR + SSE, and since all the sums of squares are positive, SSR <= SST.
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