Quiz Chapter 11.docx - Quiz Chapter 11 Question 1 If the null hypothesis that two means are equal is true where will 97 of the computed z values lie

# Quiz Chapter 11.docx - Quiz Chapter 11 Question 1 If the...

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Quiz Chapter 11 Question 1 If the null hypothesis that two means are equal is true, where will 97% of the computed z values lie between? ±2.17 Hide Feedback This is a two-tailed test, so first we split the significance level in half. The significance level is 1.00 - 0.97 = 0.03. So 0.03/2 = .015 of the area will be in each tail of the z distribution. To find the z values, we subtract the area in the tail from .5000, so .5000 - .0150 = .485. Next, we search the body of the "areas under the normal curve" table for a value as close to .4850 as possible. We locate this value and find the values 2.1 in the margin of the row and .07 in the margin of the column. So 97% of the values are between -2.17 and 2.17. Question 2 Assuming the population variances are known, the population variance of the difference between two means is _____________. The sum of the two population variances Hide Feedback We assume the means are from independent populations; thus, the variance of the difference is the sum of the variances . Question 3 When testing the difference between two population means, the sample variances are pooled to estimate the population variance when ________________. The population variances are assumed equal but unknown Hide Feedback We pool the sample variances when the population variances are not known and we assume the populations have the same variances. The pooled sample variances are the best point estimate of the population variance. Question 4 When testing the difference between two dependent population means, the test statistic is based on a ______________. Standard deviation of the differences Hide Feedback When the samples are dependent, we find the difference between the paired or related observations. The test statistic is based on the standard deviation of these differences.
Question 5 Which condition must be met to conduct a test for the difference in two sample means using a z -statistic? The two population standard deviations must be known. Hide Feedback To test for a difference between two means with a z statistic, it is necessary that we know the population standard deviations. Question 6 When is it appropriate to use the paired difference t -test? When two dependent samples are compared Hide Feedback To use the paired difference t -test, the two samples must be dependent or related. Question 7 We test for a hypothesized difference between two population means: H 0 : μ 1 = μ 2 . The population standard deviations are unknown but assumed equal. The number of observations in the first sample is 15, and 12 in the second sample. How many degrees of freedom are associated with the critical value? 25 Hide Feedback The test statistic is a t statistic, and the associated degrees of freedom are found by calculating . Question 8 For a hypothesis comparing two population means, H 0 : μ 1 ≤ μ 2, what is the critical value for a one-tailed hypothesis test, using a 5% significance level, with both sample sizes equal to 13? Assume the population standard deviations are equal.

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