Stats - W4

Q # 1

Please read the article below prior to answering the question.

EPA Water Tests

Question: How do you think the water department constructed the 95% confidence intervals for the population mean concentration of cyanide in the water?

Do the following to answer the question. ( You do not need to make any calculations.) a. What sampling distribution do you think they used? Why? b. Do you think they used the population standard deviation in calculating the margin of error? Why or why not? If not, what could they have used?

Reference Larson, R., & Farber, B. (2012) Elementary statistics: picturing the world, (5th Ed.). Boston, MA: Pearson.

Q # 2

Additional Sleep Discussion Forum

In 1908, W.S. Gosset published the article "The Probable Error of a Mean" (Biometrika, Vol. 6, pp. 1-25). In this pioneeringpaper, written under the pseudonym "Student," Gosset introduced what later became known as Student's t-distribution. Gosset used the following data set, which gives the additional sleep in hours obtained by a sample of 10 patients using laevohysocyamine hydrobromide (hereinafter referred to as "the drug"). 1.9 0.8 1.1 0.1 -0.1 4.4 5.5 1.6 4.6 3.4

a. Create a 95% confidence interval for the additional sleep that would be obtained on average for all people using the drug. Briefly explain the process that you used and why.

b. Give an interpretation of the confidence interval that you found in part a. That is, what does it mean? c. Make an inference: Was the drug effective in increasing sleep? Explain your reasoning.

Reference

Weiss, N., (2008) Elementary statistics, (7th Ed.). Boston, MA: Pearson.