ii.Based on this plot, the required condition does not appear to be met. However you can assure Harry that the interval estimate is still valid. Why is that the case? Explain briefly:
4. Coronary bypass surgery is a procedure used to reduce the risk of death from coronary artery disease. A random sample of 60 patients who had emergency bypass surgery and an independent random sample of 100 patients who had non-emergency surgery were obtained. Patients were classified according to whether they survived the surgery. The results are shown below: Survived? Surgery Type Yes No Total 1 = Emergency 48 12 60 2 = Non-emergency 88 12 100 a. A medical researcher wants to determine if the proportion that survive emergency surgeries is significantly less than the proportion that survive non- emergency surgeries at the 5% level. Let p 1 represent the population proportion of all emergency surgeries that result in survival, and p 2 represent the population proportion of all non-emergency surgeries that result in survival. State the hypothesis to be tested:  H 0 : __________________________ H a : __________________________ b. Under the null hypothesis, the two population proportions are the same. Compute the estimate of this common population proportion. Show all work.  Final answer: _______________ c. Compute the test statistic for testing the hypotheses in part (a). Show all work.  Final answer: _______________ d. Report the p -value corresponding to the hypotheses in part (a) and your test statistic in part (c). Show your work.  Final answer: _______________ e. At the 5% level, do the data provide sufficient evidence to say the population survival rate of emergency surgeries is less than the population survival rate of non-emergency surgeries?  Circle one: Yes No 197
f. If there is no difference between the two population survival rates, and we were to repeat this study many, many times, each time conducting the same hypothesis test at the same significance level, then we would expect to reject H 0 … (circle one)  ... about 95% of the time. ... about 5% of the time. Cannot be determined. 5. Does it make sense? Decide whether each statement is true or false. 6. Which Technique? – For each scenario below, determine if the most appropriate statistical analysis technique is conducting a hypothesis test (HT) or constructing a confidence interval (CI). Then also give the symbol for the corresponding parameter that is of interest. [2 points each] a. A fitness instructor is working on a project which involved having a random sample of HS students participate in a fitness course during their last semester in HS. For each student it was determined whether or not their fitness level improved. The instructor would like to assess if the improvement rate for all male students is higher than that for all female students.
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- Fall '10
- Statistics, Statistical hypothesis testing, researcher