shows data from a survey of female voters in the UK. Each voter’s age and smoking status were recorded at an initial interview. The interview was followed up 20 years later, at which point some of the original interviewees were dead and others still living, recorded in the variable <code>outcome</code>. Unsurprisingly, the older interviewees were much more likely to have died during the 20-year follow-up. The model values show the difference in mean ages between the smokers and non-smokers separately for 