For a possible 5 points.
Answer the following questions and submit your responses in a pdf.
A group of 75 college students from a certain liberal arts college were randomly sampled and asked about the number of alcoholic drinks they have in a typical week. The file containing the data is linked below. The purpose of this study was to compare the drinking habits of the students at the college to the drinking habits of college students in general. In particular, the dean of students, who initiated this study, would like to check whether the mean number of alcoholic drinks that students at his college have in a typical week differs from the mean of U.S. college students in general, which is estimated to be 4.73.
Use the data in this file (drinks.xls) downloadto answer the following questions:
1.) Using excel file calculate the mean number of drinks consumed (AVERAGE)?
2.) Using excel file calculate the standard deviation (STDEV)?
3.) Based on the text above how would you state the null and alternative hypothesis?
4.) Using the 95% confidence interval e.g. an alpha value of .05 do you accept or reject reject the null hypothesis?
5.) Now suppose that instead of the 75 students having been randomly selected from the entire student body, the 75 students had been randomly selected only from the engineering classes at the college (for the sake of convenience). Address the following two issues regarding the effect of such a change in the study design:
a. Would we still be mathematically justified in using the Confidence Interval for obtaining conclusions, as we did previously?
b. Would the resulting conclusions still address the question of interest (which, remember, was to investigate the drinking habits of the students at the college as whole)? Explain your answer using the terms generalizability, external validity, and internal validity.
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