第一次作业（Homework 1.doc

Homework 1 Applied Survival Analysis Using the data from Worcester Heart Attack Study (P. 4, Applied Survival Analysis-Regression Modeling of Time to Event Data): (1) Fit the exponential regression model to the data with both Age and Drug use as predictors (intercept is needed in this model); Derive the Maximum Likelihood Estimates (MLE) of these parameters, assuming that the errors are drawn from the distribution exp(1)(the probability density is f(x)=exp(-x)). Please give complete mathematical steps, not just results). (2) Write R codes for the regression of (1) with error specified as "exponential" (we should expect to observe the same MLE values from the R codes as the theoretical results obtained in (1)).