TEST BANK INTRODUCTION TO BUSINESS STATISTICS 7TH EDITION RONALD WEIERS

Chapter 11: Hypothesis Tests Involving Two Sample Means

1. True or False
When comparing the mean of two dependent samples, we are interested in only one variable: the difference between measurements for each person or object.
TRUE

2. True or False
A typical example of dependent samples occurs when we have before-and-after measures of the same individuals.
TRUE

3. True or False
An important factor in choosing between the pooled-variances t-test and the unequal-variances t-test is whether we can assume the population means might be equal.
FALSE

4. True or False
Although it is often associated only with small-sample tests, the t distribution is appropriate when the population standard deviations are unknown, regardless of how large or small the samples happen to be.
TRUE

5. True or False
When the population standard deviations are unknown and not assumed to be equal, pooling the sample standard deviations into a single estimate of their common population value is no longer applicable.
TRUE

6. True or False
When the population standard deviations are unknown and are not assumed to be equal, s1 and s2 must be used to estimate their respective population standard deviations, 1 and 2.
TRUE

7. True or False
The number of degrees of freedom associated with the unequal-variances t-test for comparing the means of two independent samples is n1 + n2 – 2.
FALSE

8. True or False
When either test can be applied to the same data, the z-test for comparing the means of two independent samples is preferable to the unequal-variances t-tests, especially when doing the test with computer assistance.
FALSE

9. True or False
The z-test requires no assumptions about the shape of the population distributions as long as both n1 and n2 are 30.
TRUE

10. True or False
The z-test approximation to the unequal variance t-test assumes that the population standard deviations, 1 and 2 , are known.
FALSE

11. True or False
If we wish to examine the before-and-after productivity of individual employees after a change in their workstation layout, a matched-pairs t-test is applicable.
TRUE

12. True or False
If we wish to compare the before-and-after reading speeds of individual participants in a speed-reading course, the z-test for comparing the means of two independent samples is appropriate.
FALSE