Statistics: Working with Confidence Intervals – #29484


Question: Consider the data file labeled Cholesterol Data available under Data Sets in Excel in the main menu. Here is a short description of the data set: 350 adult males between the ages of 30 and 65 participated in a study to investigate the relationship between the consumption of meat and serum cholesterol levels. Each subject ate beef as his only meat for a period of 20 weeks, pork as his only meat for another period of 20 weeks, and chicken or fish as his only meat for another 20-week period. At the end of each period serum cholesterol determinations (mg/100 ml) were made and recorded.

(a) Select a simple random sample of 20 subjects from the population of 350. Display your data values (they should be stored in 3 different columns). There should be a total of 60 data values – 20 in each in column.

(b) Is there any evidence that the mean serum cholesterol level differs in the three groups of diet? To answer the question, state the hypotheses, perform an appropriate test of hypothesis at the 5% significance level, display the EXCEL output, identify the p-value, and interpret the result, i.e., answer the question.

(c) Is there any significant difference between the mean serum cholesterol level of beef and chicken/fish diets? To answer this question, state the hypotheses, perform an appropriate test of hypothesis at the 5% significance level, determine the rejection and non-rejection regions, display the EXCEL output, identify the p-value, and interpret the result, i.e., answer the question.

(d) Find a 95% confidence interval for the population mean serum cholesterol level for pork diet and interpret the result.

(e) Find the population mean serum cholesterol level for the pork diet. Display the EXCEL output. Is this population mean included in the confidence interval calculated in part (d)?

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