Exam 11: Two-Sample Tests of Hypothesis

Which condition must be met to conduct a test for the difference in two sample means using a z-statistic?

Accounting procedures allow a business to evaluate its inventory costs based on two methods: LIFO (Last In First Out) or FIFO (First In First Out). A manufacturer evaluated its finished goods inventory (in $000s) for five products with the LIFO and FIFO methods. To analyze the difference, they computed (FIFO - LIFO) for each product. Based on the following results, does the LIFO method result in a lower cost of inventory than the FIFO method? What is the value of calculated t?

A company is researching the effectiveness of a new website design to decrease the time to access a website. Five website users were randomly selected, and their times (in seconds) to access the website with the old and new designs were recorded. To compare the times, they computed (new website design time - old website design time). The results follow. For a 0.01 significance level, what is the critical value?

For hypotheses that compare two population means, what test statistic is used when the population standard deviations are unknown?

If a hypothesis states that one population mean is greater than another population mean, then the test is _______________.

When the population standard deviations are unknown, the purpose of pooling the sample variances when testing the difference between two populations is to ___________.

A recent study focused on the number of times men and women send a Twitter message in a day. The information is summarized next. At the .01 significance level, is there a difference in the mean number of times men and women send a Twitter message in a day? Based on the p-value, what is your conclusion?

Provide two examples of when a paired t-test can be used to test a hypothesis of no difference between population means.

If the null hypothesis states that there is no difference between the two population means, then the test is ______________.

For hypotheses that compare two population means, what test statistic is used when the population standard deviations are known?

Two samples, one of size 14 and the second of size 13, are selected to test the difference between two population means. How many degrees of freedom are used to find the critical value? Assume the population standard deviations are equal.

What is the critical value of t for the claim that the difference of two means is less than zero with α = 0.025 and sample sizes of nine and seven? Assume equal population standard deviations.

A recent study focused on the amount of money single men and women save monthly. The information is summarized next. Assume that the population standard deviations are equal. At the .01 significance level, do women save more money than men? What is the value of the test statistic for this hypothesis test?

Accounting procedures allow a business to evaluate their inventory costs based on two methods: LIFO (Last In First Out) or FIFO (First In First Out). A manufacturer evaluated its finished goods inventory (in $000s) for five products with the LIFO and FIFO methods. To analyze the difference, they computed (FIFO - LIFO) for each product. Based on the following results, does the LIFO method result in a lower cost of inventory than the FIFO method? What are the degrees of freedom?

If two dependent samples of size 100 are used to test the difference between the means, the degrees of freedom for a t-statistic are _____.

What is the critical value of t for a two-tail test of the difference between two means, a level of significance of 0.10 and sample sizes of 7 and 15? Assume equal population standard deviations.

A company is researching the effectiveness of a new website design to decrease the time to access a website. Five website users were randomly selected, and their times (in seconds) to access the website with the old and new designs were recorded. To compare the times, they computed (new website design time - old website design time). The results follow. What is the value of the test statistic?

If two dependent samples of size 20 are used to test the difference between the means, the degrees of freedom for a t-statistic are 19.

When independent samples are used to test for differences in the population means with equal but unknown population standard deviations, we _______ these sample standard deviations.

When testing the hypothesized equality of two population means, the implied null hypothesis is ____________.