Suppose that you want to perform a hypothesis test to compare the means of two populations, using independent simple random samples. Assume that the two distributions of the variable under consideration have the same shape, but are not normal, and both sample sizes are large. Answer the following questions and explain your answers.

a. Is it permissible to use the pooled t-test to perform the hypothesis test?

b. Is it permissible to use the Mann-Whitney test to perform the hypothesis test?

c. Which procedure is preferable, the pooled t-test or the Mann-Whitney test?

Short Answer

Expert verified

a). Yes, the hypothesis test can be performed using a pooled t-test in the provided case.

b). Yes, the Mann-Whitney test is appropriate for completing the hypothesis test in the given circumstance.

c). Mann-Whitney test is the preferable method.

Step by step solution

01

Part (a) Step 1: Given Information

Independent samples from two populations of the same variable have the same shape, but they are not normal, and both samples are huge.

02

Part (a) Step 2: Explanation

For comparing two population means, the following assumptions are made when using the pooled t - test and pooled t - interval test.

1.) Random variables that are easy to understand

2.) Samples from different people

3) A large sample or a normal population.

4.) The population standard deviation is the same.

Independent samples from two populations of the variable under examination have the same shape but are not normal, and both samples are large, according to the information provided.

There is no way of knowing if the sample standard deviations of two populations are comparable or equal. If assumption 4 is true, then the hypothesis test can be performed using a pooled t- test in the provided case.

03

Part (b) Step 1: Given Information

Independent samples from two populations of the same variable have the same shape, but they are not normal, and both samples are huge.

04

Part (b) Step 2: Explanation

A nonparametric approach is used to compare the means of two populations when the samples are not normal and the samples are not huge.

The Mann-Whitney test is a nonparametric test that is employed when samples are independent and the two sample distributions of the variable under consideration (one from each population) have the same shape.

Independent samples from two populations of the variable under examination have the same shape, but are not normal, and both samples are large, according to the information provided.

05

Part (c) Step 1: Given Information

Independent samples from two populations of the same variable have the same shape, but they are not normal, and both samples are huge.

06

Part (c) Step 2: Explanation

From part, a and b of this exercise, clearly Mann-Whitney test is the preferable method.

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Most popular questions from this chapter

In each of Exercises 10.75-10.80, we have provided summary statistics for independent simple random samples from non populations. In each case, use the non pooledt-test and the non pooled t-interval procedure to conduct the required hypothesis test and obtain the specified confidence interval.

x~1=10,s1=2,n1=15,x~2=12,s2=5,n2=15

a. Two-tailed testα=0.05.

b. 95%confidence interval.

The intent is to employ the sample data to perform a hypothesis test to compare the means of the two populations from which the data were obtained. In each case, decide which of the procedures should be applied.

Independent: n1=40

n2=45

Left-Tailed Hypothesis Tests and CIs. If the assumptions for a pooled t-interval are satisfied, the formula for a (1-α)-level upper confidence bound for the difference, μ1-μ2, between two population means is

x¯1-x~2+ta·Sp1/n1+1/n2

For a left-tailed hypothesis test at the significance level α, the null hypothesis H0:μ1=μ2will be rejected in favor of the alternative hypothesis Ha:μ1<μ2if and only if the (1-α)-level upper confidence bound for μ1-μ2is less than or equal to 0. In each case, illustrate the preceding relationship by obtaining the appropriate upper confidence bound and comparing the result to the conclusion of the hypothesis test in the specified exercise.

a. Exercise 10.45

b. Exercise 10.46

In each of exercise 10.13-10.18, we have presented a confidence interval for the difference,μ1-μ2, between two population means. interpret each confidence interval

99%CI from-10to5

In this Exercise, we have provided summary statistics for independent simple random samples from two populations. In each case, use the pooled t-lest and the pooled t-interval procedure to conduct the required hypothesis test and obtain the specified confidence interval.

x¯1=20,s1=4,n1=10,x¯2=18,s2=5,n2=15

a. Right-tailed test,α=0.05

b. 90%confidence interval

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