In each of Exercises 10.35-10.38, we have provided summary statistics for independent simple random samples from two populations. Preliminary data analyses indicate that the variable under consideration is normally distributed on each population. Decide, in each case, whether use of the pooled t-lest and pooled t-interval procedure is reasonable. Explain your answer.

10.36 x¯1=115.1,s1=79.4,n1=51
x¯2=24.3,s2=10.5,n2=19

Short Answer

Expert verified

Not reasonable. pooled t- test and pooled t- interval test are not appropriate for comparing two population means.

Step by step solution

01

Given information

To explain the use of pooled t- test and pooled t-interval test is reasonable with the given sample data.

x¯1=115.1,s1=79.4,n1=51

x¯2=24.3,s2=10.5,n2=19

02

Explanation

For comparing two population means, the following assumptions are made when using the pooled t- test and pooled t- interval test.
(1) Simple random variables
(2) Independent samples
(3) Normal population or large samples.

In the case of large samples, this pooled t- test is resilient to moderate violation.
(4) Equal population standard deviation.

In the case of nearly equal sample sizes, this pooled t- test is robust for modest violation.
Assumptions 1and 2 are correct based on the information provided.
Because both populations are regularly distributed and the sample sizes are high (n1=57,n2=19), assumption 3 is also confirmed.
However, the standard deviation of two populations s1=79.4and s2=10.5 is vastly different.
This violates assumption 4 .
As a result, pooled t- test and pooled t- interval test are not reasonable for comparing two population means.

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Most popular questions from this chapter

Stressed-Out Bus Drivers. An intervention program designed by the Stockholm Transit District was implemented to improve the work conditions of the city's bus drivers. Improvements were evaluated by G. Evans et al., who collected physiological and psychological data for bus drivers who drove on the improved routes (intervention) and for drivers who were assigned the normal routes (control). Their findings were published in the article "Hassles on the Job: A Study of a Job Intervention with Urban Bus Drivers" (Journal of Organizational Behavior, Vol. 20, pp. 199-208). Following are data, based on the results of the study, for the heart rates, in beats per minute, of the intervention and control drivers.

a. At the 5%significance level, do the data provide sufficient evidence to conclude that the intervention program reduces mean heart rate of urban bus drivers in Stockholm? (Note; x1=67.90, s1=5.49,x¯2=66.81and s2=9.04.

b. Can you provide an explanation for the somewhat surprising results of the study?

c. Is the study a designed experiment or an observational study? plain your answer.

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a. uniform.

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c. moderately skewed but otherwise roughly bell-shaped.

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