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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.
10.35 x¯1=468.3,s1=38.2,n1=6

x2=394.6,s2=84.7,n2=14

Short Answer

Expert verified

No, that isn't reasonable. Because the sample standard deviations indicate that the two population standard deviations are not identical and the sample sizes are not roughly equal.

Step by step solution

01

Given information

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

x¯1=468.3,s1=38.2,n1=6
x2=394.6,s2=84.7,n2=14

02

Explanation

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

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

Note that: 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.
Assumption 3 is also confirmed because two populations are regularly distributed.
Yet, there is a significant difference in standard deviation between the two populations.
s1=38.2and s2=84.7.
Assumption 4 is violates.
As a result, Not reasonable.
Because the sample standard deviations indicate that the two population standard deviations are not identical and the sample sizes are not roughly equal.

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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.

The sample standard deviations are 23.6 and 25.2, and each sample size is 25 .

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.
10.37 x¯1=118,s1=12.04,n1=99
x2=110,s2=11.25,n2=80

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

x~1=20,s1=2,n1=30,x2=18,s2=5,n2=40.

a. Right-tailed test, α=0.05

b. 90%confidence interval.

Two-Tailed Hypothesis Tests and CIs. As we mentioned on page 413, the following relationship holds between hypothesis tests and confidence intervals: For a two-tailed hypothesis test at the significance level α, the null hypothesis H0:μ1=μ2 will be rejected in favor of the alternative hypothesis H2:μ1μ2 if and only if the (1-α)-level confidence interval for μ1-μ2 does not contain 0. In each case, illustrate the preceding relationship by comparing the results of the hypothesis test and confidence interval in the specified exercises.

a. Exercises 10.81 and 10.87

b. Excrcises 10.86 and 10.92

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