## 9.10 Exercises

### 9.10.1 Exercise

Investigate the association between sex and 5-year mortality for patients who have undergone surgery for melanoma.

First recode the variables as shown in the text, then plot the counts and proportions for 5-year disease-specific mortality in women and men. Is there an association between sex and mortality?

### 9.10.2 Exercise

Make a table showing the relationship between sex and the variables age, T-stage and ulceration. Hint: summary_factorlist(). Express age in terms of median and interquartile range. Include a statistical comparison.

What associations do you see?

### 9.10.3 Exercise

Run a logistic regression model for 5-year disease-specific mortality including sex, age, T-stage and ulceration.

What is the c-statistic for this model?

Is there a relationship between sex and mortality, after adjustment for the other explanatory variables?

### 9.10.4 Exercise

Make an odds ratio plot for this model.