Question 2. A population of 100 healthy women was recruited from the internal medicine practice at  UMC from Jun

Question 2. A population of 100 healthy women was recruited from the internal medicine practice at
UMC from June 1 – June 30, 2000 and followed for the development of breast cancer. Twelve women developed breast cancer after each was followed for 4 years. Ten women who remained healthy were followed for 2 years and then were lost to follow-up. Five women died of heart disease after 6 years of follow-up. These 5 women did not develop breast cancer. The remaining women remained healthy and were each followed for 10 years.
a. Calculate the cumulative incidence of breast cancer in this population and interpret the result
in 1-2 sentences. (5 pts)
Cumulative Incidence                = # new (incident) cases/total population at risk
CI                                                  =
b. Calculate the number of person-years of observation that was accrued by this population.
(5 pts)
c. Calculate the incidence rate and interpret the result in 1-2 sentences. (5 pts)
Incidence Rate                           = # new (incident) cases/person-time contributed by population at risk
IR                                                 =
d. Which measure of disease incidence – cumulative incidence or incidence rate – is more
appropriate in this situation? Why? (5 pts)