Exam 13: Hypothesis Testing: Comparing Two Populations

In testing the difference between the means of two normal populations, using two independent samples, when the population variances are unknown and unequal, the sampling distribution of the resulting statistic is:

For testing the difference between two population proportions, the pooled proportion estimate should be used to compute the value of the test statistic when the:

A t test for testing the difference between two population means from two independent samples is the same as the t test to test the difference of two population means in a matched pairs experiment.

In testing the hypotheses: H0: p1 - p2 =0 HA: p1 - p2 > 0, we found the following statistics: n1 = 350, x1 = 178. n2 = 250, x2 = 112. a. What is the p-value of the test? b. Use the p-value to test the hypotheses at the 10% level of significance.

In testing whether the means of two normal populations are equal, summary statistics computed for two independent samples are as follows: n1 = 25, $\bar { X } _ { 1 }$ = 7.30, s1 = 1.05. N2 = 30, $\bar { X } _ { 2 }$ = 6.80, s2 = 1.20. Assume that the population variances are equal. Then the standard error of the sampling distribution of the sample mean difference $\bar { X } _ { 1 } - \bar { X } _ { 2 }$ is equal to:

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 $\bar { X } _ { 1 } - \bar { X } _ { 2 }$ if the:

A sample of size 150 from population 1 has 40 successes. A sample of size 250 from population 2 has 30 successes. The value of the test statistic for testing the null hypothesis that the proportion of successes in population 1 exceeds the proportion of successes in population 2 by 0.05 is:

A quality control inspector keeps a tally sheet of the numbers of acceptable and unacceptable products that come off two different production lines. The completed sheet is shown below. Production line Acceptable products Unacceptable products 1 152 48 2 136 54 Can the inspector infer at the 5% significance level that production line 1 is doing a better job than production line 2?

Which of the following is a required condition for using the normal approximation to the binomial distribution in testing the difference between two population proportions?