(a) Consider the data given in Exercise Table 3.3. Examine the relationshipbetween remission duration and survival time for each of the nine possible prognostic variables: age, gender, family history...

(a) Consider the data given in Exercise Table 3.3. Examine the relationshipbetween remission duration and survival time for each of the nine possible prognostic variables: age, gender, family history of melanoma, and the six skin tests. Groupthe patients according to different cutoff points. Estimate and draw remission and survival curves for each subgroup. Compare remission and survival distribution of subgroups using the methods discussed in Chapter 5. Prepare tables similar to Table 3.8.

(b) Use Cox’s regression model to identify the significant variables in part (a) for their relative importance to remission duration and survival time. Check the appropriateness of the proportional hazards model using the significant variables identified and the stratified analysis and weighted Shoenfeld residuals. Interpret the results.