Chapter 10: Q.10.9 (page 405)
The primary concern is deciding whether the mean of Population 1 is less than the mean of Population 2.
Short Answer
(a) Null hypotheses:
Alternate hypotheses:
(b) The hypotheses test is left-tailed.
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Chapter 10: Q.10.9 (page 405)
The primary concern is deciding whether the mean of Population 1 is less than the mean of Population 2.
(a) Null hypotheses:
Alternate hypotheses:
(b) The hypotheses test is left-tailed.
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Give an example of interest to you for comparing two population means. Identify the variable under consideration and the two populations.
Wing Length. D. Cristol al. published results of their studies of two subspecies of dark-eyed juncos in the article "Migratory Dark-Eyed Juncos, Junes Hyemalix, Have Better Spatial Memory and Denser Hippocampal Neurons than Nommigrtory Conspecifics" Animal behavior, Vol, 66, pp. 317-328). One of the subspecies migrates each year, and the other does not migrate. Several
physical characteristics of 14 binds of each subspecies were measured, one of which was wing length. The following data, based on results obtained by the researchers, provide the wing lengths, in millimeters (mm) for the samples of two subpecies.:
Phyllodes Tumors. Phyllodes tumors of the breast are rare tumors that represent less than one percent of growths in the breast. Researchers I. Youn et al. presented characteristics of phyllodes tumors in the article "Phyllodes Tumors of the Breast: Ultrasonographic Findings and Diagnostic Performance of Ultrasound-Guided Core Needle Biopsy" . The following table provides summary statistics for the sizes, in millimeters (mm), of independent samples of benign and malignant phyllodes tumors.

At the significance level, do the data provide sufficient evidence to conclude that, on average, malignant phyllodes tumors are larger than benign phyllodes tumors?
Suppose that you want to perform a hypothesis test to compare the means of two populations, using a paired sample. For each part, decide whether you would use the paired -test, the paired Wilcoxon signed-rank test, or neither of these tests if preliminary data analyses of the sample of paired differences suggest that the distribution of the paired-difference variable is
a. approximately normal.
b. highly skewed; the sample size is .
c. symmetric bimodal.
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 pooled test and the non pooled interval procedure to conduct the required hypothesis test and obtain the specified confidence interval.
a. Two-tailed test,
b. confidence interval.
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