GRADED ASSIGNMENT!! Only the student’s instructor may help.
Name: __________________________ score: _________________
YOU BE THE STATISTICIAN DUE DATE 12/03/12
In all three parts of this question, you are a statistical consultant in a research lab.
Part 1
A medical research worker prepares and reports cholesterol data for two groups of six patients each. The researcher submits the following to you, the statistician, and asks whether the treatment significantly altered the cholesterol readings in either direction (use p = 0.05 as the cutoff for statistical significance).
Control 
Treated 
362 
194 
211 
277 
320 
201 
276 
164 
288 
304 
321 
199 
You call the researcher after receiving the data. There were only the data – no writeup of how the experiment was done. (FYI: This is called a protocol.) The researcher has left for a twoweek vacation in Florida, but the assistant assures you that the control patients were a different set than the treated patients and the two groups (total of 20) were randomly selected. You are to perform the appropriate twosample test on the data (αlevel 0.05) and write a report for the researcher.
a. Summary statistics (1 POINTS):

Control 
Treated 
Mean 


Standard Deviation 


b. Test (1 POINTS):
H_{O}
H_{A}
c. p – value (1 POINTS) (assume equal variances (I.E. NOT POOLED)) __________
d. 95% Confidence Interval around the mean (1 POINTS): ( , )
e. Report to the researcher (2 POINTS): Write brief statements on the results of both the confidence interval and the hypothesis test.
Part 2
It is two weeks later. Back from Florida, the researcher reads your report and finds that you did not treat the data as paired! They were, in fact, paired – the patients were tested first, then given the medication and tested again! The assistant had misinformed you! (Hey, this happens !!!). The correct table is

Patient 1 
Patient 2 
Patient 3 
Patient 4 
Patient 5 
Patient 6 
Pretreatment 
362 
211 
320 
276 
288 
321 
Treated 
194 
277 
201 
164 
304 
199 
You must now redo the report. Use alphalevel 0.05 as before.
a. Summary statistics (1 POINTS):

Difference 
Mean 

Standard Deviation 

b. Test (1 POINTS):
H_{O}
H_{A}
c. p – value is (1 POINTS) _______
d. 95% Confidence Interval around the mean (1 POINTS): ( , )
e. Report to the researcher (2 POINTS): Write statements on the results of both the confidence interval and the hypothesis test.
f. Add to your report a short tactful, clear, grammatically correct explanation of why it was necessary to redo the statistical analysis. In your report, tell what the difference was in your conclusion and explain the difference between independent and paired samples in a way that a nonstatistician would understand. Remember: Be tactful! (2 POINTS)
Part 3
A week has passed. The researcher emails you and is writing his report. His boss asks him for a specific recommendation on whether the medication should be massproduced (yes or no!) The researcher is apprehensive about making the wrong decision. For the correct hypothesis that you tested,
a. Describe to the researcher in terms of his study what the Type I error is. What could be the effect on the company? (2 POINTS)
b. Describe to the researcher in terms of his study what the Type II error is. What could be the effect on the company? (2 POINTS)
c. By now, you are very unsure about the researcher. You begin to wonder if the
assumptions and conditions have been met for the correct ttest that you did.
Name the assumptions and conditions for the test and describing them in a way
that a nonstatistician would understand. (2 POINTS)
Subject  Mathematics 
Due By (Pacific Time)  01/15/2013 10pm 
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