As part of a study investigating the effects of vigorous exercise on risk of coronary heard...

As part of a study investigating the effects of vigorous exercise on risk of coronary heard disease, researchers measured HDL concentrations (mg/dL) in a sample of 19 male marathon runners as well as in a sample of 32 men who do not regularly exercise. The data are summarized below: Mean St. Dev. Marathon runners 51.3 mg/dL 14.2 mg/dL Do not exercise 44.0 mg/dL 15.0 mg/dL a. Assuming that the two distributions of HDL concentrations are normally distributed with equal variances, run the appropriate test to determine if there is a significant difference between marathon runners and men who don’t exercise. Given: critical = 2.00 and SePooled = 2.43 mg/dl (4pts) b. Name a possible confounding variable in this analysis and what impact it might have on the applicability of the results.

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