Chapter24 - STA2023 Chapter 24 (Comparing Means) Skip:...

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1 STA2023 – Chapter 24 (Comparing Means) Skip: “Back Into The Pool” through the end of the chapter (pages 630 – 634) In the last chapter you learned how to make inferences for the mean ( μ ) of a single population. This chapter addresses making inferences for comparing two population means ( 1 versus 2 ). Activity 1: A physical therapist claims that women are more flexible than men. She measures the flexibility of 35 randomly selected adult women in Gainesville and 45 randomly selected adult men in Gainesville by determining the number of inches subjects could reach while sitting on the floor with their legs straight out and back perpendicular to the ground. The more flexible an individual is, the further they can reach. Analysis of the sample data yielded the summary statistics shown here: Women Men Sample Size 35 45 Sample Mean (in inches) 20.3 18.7 Sample St. Dev. (in inches) 2.1 3.4 A. Describe the two populations of interest to this study. Since there are two populations being compared, this is a 2-sample study Population 1: Population 2: B. Given that the data was collected randomly, is the flexibility of women and men subjects in the study dependent on each other, or independent of each other? Note that the standard deviations of the populations ( 1 2 , σ ) are not known. Therefore, we will use the sample standard deviations ( s 1 , s 2 ) in our computations. This implies that we will be using t-procedures, not z-procedures. The appropriate confidence interval is called a two-sample t-interval and the appropriate hypothesis test is called a two-sample t-test . Also note that the sample sizes are not equal.
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This note was uploaded on 11/22/2010 for the course STA 2023 taught by Professor Ripol during the Spring '08 term at University of Florida.

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Chapter24 - STA2023 Chapter 24 (Comparing Means) Skip:...

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