1. In testing the difference between two population means using two independent samples, we use thepooled variance in estimating the standard error of the sampling distribution of the sample mean differencex¯1 - x¯2 if the
A. populations are nonnormal with unequal variances.
B. sizes are both greater than 30.
C. populations are at least normally distributed with equal variances.
D. ample sizes are both large.
2. The vertical distances between observed and predicted values of y are called
A. errors of prediction.
B. least square lines.
C. scatterplots.
D. methods of least squares.
3. In testing for the equality of two population variances, when the populations are normally distributed, the10% level of significance has been used. To determine the rejection region, it will be necessary to refer tothe F table corresponding to an upper-tail area of
A. 0.90.
B. 0.05.
C. 0.20.
D. 0.10.
4. Consider the following data values of variables x and y.
Find the least squares regression line.
x 4 2 6 4 3
y 5 3 7 6 5
A. 1.659 + 0.932x
B. 21.206 + 1.073x
C. 1.122 + 1.073x
D. -1.045 + 0.932x
5. A random sample of males and females involved in rear-end accidents results in the following Minitabsummary:
What is the standard error of the statistic between the two means?
N MEAN MEDIAN TRMEAN STDEV SEMEAN
FEMALES 33 23.91 20.00 23.38 9.77 1.70
MALES 38 28.87 28.50 28.44 9.67 1.57
A. 2.314
B. 0.897
C. 1.635
D. 4.96
6. A "best-fit" mathematical equation for the values of two variables, x and y, is called
A. regression analysis.
B. correlation analysis.
C. scatter diagram.
D. errors of prediction.
7. With larger and larger numbers of categories in chi-square tests, the chi-square distribution takes on theshape of the _______ distribution.
A. normal
B. t-
C. Poisson
D. binomial
8. Which of the following statements are true regarding the simple linear regression model yi = ß0 + ß1xi +ei?
A. ß1 is the y-intercept of the regression line.
B. ei is a nonrandom error.
C. yi is a value of the dependent variable (y) and xi is a value of the independent variable (x).
D. ß0 is the slope of the regression line.
9. A left-tail area in the chi-square distribution equals 0.95. For df = 10, the table value equals
A. 20.483.
B. 3.940.
C. 18.307.
D. 15.987.
10. Given the significance level 0.025, the F-value for the degrees of freedom, df = (7,3) is
A. 27.67.
B. 5.89.
C. 8.45.
D. 14.62.