Develop a life table similar to Table 4.16, giving the number of people who remained abstinent at 1, 2, . . . , 12 months of life (assume for simplicity that there are 30 days in each of the first 11 months after quitting and 35 days in the 12th month). Plot these data on the computer using either Excel or R or some other statistical package. Compute the probability that a person will remain abstinent at 1, 3, 6, and 12 months after quitting.

Table 4.16: Number of infants (of 2500) who remain disease-free at the end of each month during the first year of life

______________ Disease-free infants at
i .......................... the end of month i
0 ...................................................... 2500
1 ...................................................... 2425
2 ...................................................... 2375
3 ...................................................... 2300
4 ...................................................... 2180
5 ...................................................... 2000
6 ...................................................... 1875
7 ...................................................... 1700
8 ...................................................... 1500
9 ...................................................... 1300
10 ................................................... 1250
11 ................................................... 1225
12 ................................................... 1200

Health Promotion
A study was conducted among 234 people who had expressed a desire to stop smoking but who had not yet stopped. On the day they quit smoking, their carbonmonoxide level (CO) was measured and the time was noted from the time they smoked their last cigarette to the time of the CO measurement. The CO level provides an “objective” indicator of the number of cigarettes smoked per day during the time immediately before the quit attempt. However, it is known to also be influenced by the time since the last cigarette was smoked. Thus, this time is provided as well as a “corrected CO level,” which is adjusted for the time since the last cigarette was smoked. Information is also provided on the age and sex of the participants as well as each participant’s self-report of the number of cigarettes smoked per day. The participants were followed for 1 year for the purpose of determining the number of days they remained abstinent. Number of days abstinent ranged from 0 for those who quit for less than 1 day to 365 for those who were abstinent for the full year. Assume all people were followed for the entire year.