Exam 11: Two-Sample Tests of Hypothesis

Administering the same test to a group of 15 students and a second group of 15 students to see which group scores higher is an example of

If we are testing for the difference between two population means and assume that the two populations have equal and unknown standard deviations, the standard deviations are _____.

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

For a hypothesis comparing two population means, what is the critical value for a one-tailed hypothesis test, using a 5% level of significance level, with both sample sizes equal to 13? Assume the population standard deviations are equal.

In a market test of a new chocolate raspberry coffee, a poll of 400 people (sample 1) from Dobbs Ferry showed 250 preferred the new coffee. In Irvington, 170 (sample 2) out of 350 people preferred the new coffee. To test the hypothesis that a higher proportion of people in Dobbs Ferry prefer the new coffee, what is the alternate hypothesis?

A statistics professor wants to compare grades in two different classes of the same course. This is an example of a paired sample.

The paired difference test has ___________ degrees of freedom.

When testing the difference between two population means, the variances are pooled when

When dependent samples are used to test for differences in the means, we compute paired differences.

To compare the effect of weather on sales of soft drinks, a soda manufacturer sampled two regions of the country with the following results. Is there a difference in sales between the 2 regions? What is the z- test statistic? _____________