# Statistics for Management and Economics Web Quizzing Chapter 12

Statistics for Management and Economics Web Quizzing Chapter 12

WebQuizzing – Ch. 12

Book ISBN-10 0538477490

Book ISBN-13 9780538477499

Author: Gerald Keller

Title: Statistics for Management and Economics

Ed:  9e

1. The expected value of the difference of two sample means equals the difference of the corresponding population means when:
• the populations are normally distributed.
• the samples are independent.
• the populations are approximately normal and the sample sizes are large.
• All of these choices are true.
1. In testing the difference between the means of two normally distributed populations, the number of degrees of freedom associated with the unequal-variances t-test statistic usually results in a non-integer number. It is recommended that you:
• round to the nearest integer.
• change the sample sizes until the number of degrees of freedom becomes an integer.
• assume that the population variances are equal, and then use df =.
• None of these choices.

1. The quantity is called the pooled variance estimate of the common variance of two unknown but equal population variances.  It is the weighted average of the two sample variances, where the weights represent the:
• sample variances.
• sample standard deviations.
• degrees of freedom for each sample. (Sample Answer)
• None of these choices.
1. In testing the difference between two population variances are unknown and not assumed to be equal, two independent samples are drawn from the populations. Which of the following tests is appropriate?
• z-test.
• pooled variances t-test.
• unequal variances t-test.
• None of these choices.

1. In testing the difference between the means of two normal populations using two independent samples when the population variances are unequal, the sampling distribution of the resulting statistic is:
• normal
• Student-t
• approximately normal
• approximately Student-t
1. 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 if:
• the sample sizes are both large.
• the populations are normal with equal variances.
• the populations are non-normal with unequal variances.
• All of these choices are true.
1. In constructing a confidence interval estimate for the difference between the means of two independent normally distributed populations, we:
• pool the sample variances when the unknown population variances are equal.
• pool the sample variances when the population variances are known and equal.
• pool the sample variances when the population means are equal.
• never pool the sample variances.
1. The t-test for the difference between the means of two independent populations assumes that the respective:
• sample sizes are equal.
• means are equal.
• populations are normal.
• All of these choices are true.
1. If some natural relationship exists between each pair of observations that provides a logical reason to compare the first observation of sample 1 with the first observation of sample 2, the second observation of sample 1 with the second observation of sample 2, and so on, the samples are referred to as:
• matched pairs.
• independent samples.
• nonrandom samples.
• None of these choices.
1. The symbol refers to:
• the difference in the means of two independent populations.
• one matched pairs difference.
• the mean difference in the pairs of observations.
• None of these choices.

11. A test is being conducted to test the difference between two population means using data that are gathered from a matched pairs experiment. If the paired differences are normal, then the distribution used for testing is the:

• normal distribution.
• binomial distribution. 