A standardized residual is:
A) equal to the sum of the residuals divided by n-1.
B) the ratio of each residual divided by an estimate for the standard deviation of the residuals.
C) a value that is normally distributed with a mean equal to zero and a standard deviation equal to one.
D) None of the above
Q. 2The following data for the dependent variable, y, and the independent variable, x, have been collected using simple random sampling:
x y
10 120
14 130
16 170
12 150
20 200
18 180
16 190
14 150
16 160
18 200
Compute the correlation coefficient.
A) 0.52
B) 0.71
C) 0.62
D) 0.89
Q. 3Which one of the following is not a source of variation?
A) People
B) Measurement
C) Materials
D) Control
Q. 4If the residuals have a constant variance, which of the following should be evident?
A) The residuals should have a variance equal to zero for all levels of the independent variable.
B) The plot of the residuals against each x variable should show that the spread in the residuals is about the same at all levels of each of the independent variables.
C) The average residual should be about zero and the residual standard deviation should be approximately 1.
D) None of the above
Q. 5A company that fills soft drinks into bottles has established an -chart and an R-chart to monitor the average fill level in the bottles. To do this, the company has taken a series of samples of size n = 4 bottles. The overall average fill is 12.
03 ounces. The average range for the subgroups has been .06 ounces. Suppose, after developing the control chart, a subgroup of size 4 yields a sample mean of 12.09 ounces and a range of .08, which of the following statements is true?A) The process is in control on both the -chart and the R-chart.
B) The process is out of control on the R-chart but in control on the -chart.
C) The process is out of control on the -chart but in control on the R-chart.
D) The process is out of control on both the -chart and the R-chart.
Q. 6An industry study was recently conducted in which the sample correlation between units sold and marketing expenses was 0.57. The sample size for the study included 15 companies.
Based on the sample results, test to determine whether there is a significant positive correlation between these two variables. Use an alpha = 0.05A) Because t = 2.50 > 1.7709, do not reject the null hypothesis. There is not sufficient evidence to conclude there is a positive linear relationship between sales units and marketing expense for companies in this industry.
B) Because t = 2.50 > 1.7709, reject the null hypothesis. There is sufficient evidence to conclude there is a positive linear relationship between sales units and marketing expense for companies in this industry.
C) Because t = 3.13 > 1.7709, do not reject the null hypothesis. There is not sufficient evidence to conclude there is a positive linear relationship between sales units and marketing expense for companies in this industry.
D) Because t = 3.13 > 1.7709, reject the null hypothesis. There is sufficient evidence to conclude there is a positive linear relationship between sales units and marketing expense for companies in this industry.
Q. 7The assumption that the errors or residuals are independent is best checked by:
A) looking at a normal probability plot of the residuals.
B) looking a scatter plot of each x versus y.
C) looking at a residual plot versus x and checking for curvature.
D) looking at a plot of the residuals versus time and checking for trends.
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