Inferences and Linear Regression
1. In testing the difference between two population means using two independent samples, the sampling distribution of the sample mean difference x¯1 - x¯2 is normal if the
A. populations are nonnormal and the sample sizes are large.
B. sizes are both greater than 30.
C. populations are normal.
D. population sizes are both greater than 30.
2. A balanced experiment requires that
A. the number of treatments equals the number of samples.
B. an equal number of persons or test units receives each treatment.
C. at least one sample equal size is 30.
D. at least two treatment groups be used.
3. A regression analysis between sales (in $1000) and advertising (in $) resulted in the following least squares line: yˆ = 80,000 + 5x. This implies that an increase of in advertising is expected to result in an increase of in sales.
A. $1, $5,000
B. $1, $5
C. $1, $80,005
D. $5, $5,000
4. Given the significance level 0.025, the F-value for the degrees of freedom, df = (7,3) is
A. 8.45.
B. 14.62.
C. 5.89.
D. 27.67.
5. The object on which the response and factors are observed is called
A. factor level.
B. treatments.
C. factors.
D. experimental unit.
6. In testing for the equality of two population variances, when the populations are normally distributed, the 10% level of significance has been used. To determine the rejection region, it will be necessary to refer to the F table corresponding to an upper-tail area of
A. 0.05.
B. 0.20.
C. 0.10.
D. 0.90.
7. In testing a population variance or constructing a confidence interval for the population variance, an essential assumption is that
A. sample size exceeds 30.
B. the population is normally distributed.
C. expected frequencies equal or exceed 5.
D. the population is uniformly distributed.
8. With larger and larger numbers of categories in chi-square tests, the chi-square distribution takes on the shape of the distribution.
A. t-
B. Poisson
C. normal
D. binomial
9. A random sample of males and females involved in rear-end accidents results in the following Minitab summary:
N MEAN MEDIAN TRMEAN STDEV SEMEAN
FEMALES 33
38 23.91 20.00 23.38 9.77 1.70
MALES 28.87 28.50 28.44 9.67 1.57
What is the value of the test statistic (Z score)?
A. 1.64
B. -2.14
C. 2.32
D. -4.96
10. The F-statistic in a one-way ANOVA represents the variation
A. within the treatments divided by the variation between the treatments.
B. between the treatments divided by the variation within the treatments.
C. between the treatments plus the variation within the treatments.
D. within the treatments minus the variation between the treatments.
11. A "best-fit" mathematical equation for the values of two variables, x and y, is called
A. scatter diagram.
B. errors of prediction.
C. correlation analysis.
D. regression analysis.
12. An indication of no linear relationship between two variables would be a coefficient of
A. correlation of 0.
B. determination equal to -1.
C. determination equal to 1.
D. correlation equal to -1.
13. In using the ANOVA models, the assumptions made about the data are
A. the samples are independent.
B. the population distributions are normal.
C. all 3 assumptions made here about the data.
D. the population variances are equal.
14. A random sample of males and females involved in rear-end accidents results in the following Minitab summary:
|
N
|
MEAN
|
MEDIAN
|
TRMEAN
|
STDEV
|
SEMEAN
|
|
FEMALES
|
33
38
|
23.91
|
20.00
|
23.38
|
9.77
|
1.70
|
|
MALES
|
28.87
|
28.50
|
28.44
|
9.67
|
1.57
|
What is the standard error of the statistic between the two means?
A. 2.314
B. 0.897
C. 4.96
D. 1.635
15. What is the slope of the line that passes through the points (-5, -8) and (3,8)?
A. -2
B. 2
C. -½
D. ½
16. In testing the difference between two population means using two independent samples, we use the pooled variance in estimating the standard error of the sampling distribution of the sample mean difference x¯1 - x¯2 if the
A. populations are at least normally distributed with equal variances.
B. sizes are both greater than 30.
C. populations are nonnormal with unequal variances.
D. ample sizes are both large.
17. Another name for the residual term in a regression equation is
A. residual analysis.
B. random error.
C. pooled variances.
D. homoscedasticity.
18. 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.
19. In a hypothesis test for the population variance, the alternate hypothesis is the population variance does not equal 17.0. The significance level to be used is 0.05 and the sample size to be taken is 25. The table value(s) to use from the chi-square distribution is/are
A. 13.120 and 40.647.
B. 40.647.
C. 12.401 and 39.364.
D. 39.364.
20. Given the significance level 0.05, the F-value for the degrees of freedom, df = (3,7) is
A. 4.35.
B. 8.89.
C. 6.16.
D. 4.12.