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Assignment 4

# Assignment 4 - PHC 6020 Homework Assignment 4 Due...

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PHC 6020 – Homework Assignment 4 Due Tuesday November 29, 2011 (Please show all your work, i.e. the steps that are necessary to reach your results.) 1. (16 pts) In the table below are the results of a small clinical trial comparing two treatments. The endpoint of interest is time to death (in years) which may be right censored. Treatment A Treatment B Time to failure or censoring Failure indicator Time to failure or censoring Failure indicator 1.43 1 2.30 1 0.95 0 1.98 1 3.89 0 4.03 0 2.25 1 3.30 1 0.73 1 4.20 0 3.24 1 1.58 1 Using only a calculator and showing all your work (i.e. risk set calculations) a. Combining the two treatments together compute and plot the Kaplan-Meier estimator of the survival curve together with the estimated standard error of this estimator. b. Test the null hypothesis of equality of the treatment specific survival distributions using a two-sided logrank test. Compute the standardized test statistic and the p-value. 2. (16 pts) In designing a clinical trial the investigators tell you that the standard treatment used for the treatment of multiple myeoloma results in a median survival of 4.0 years and that the survival distribution is well approximated by an exponential distribution. A new promising treatment is to be tested against the standard treatment in a two-arm randomized clinical trial with equal allocation to both arms. After quizzing the investigators they decide that they want 90% power to detect a significant difference using a one-sided logrank test at the .05 level of significance if the new treatment can increase the median survival to 5.0 years. Again after quizzing

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Assignment 4 - PHC 6020 Homework Assignment 4 Due...

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