Answer:
1. The baseline prevalence of breast cancer is:
= 0.12%.
Interpretation: 0.12% of the starting population was diagnosed with breast cancer.
2. The one-year cumulative incidence (incidence proportion) for each of the three years:
Time Starting Breast Lost to Cumulative
Population Cancer Follow-up Incidence
Start 20,000 24 0
1980 19,976 50 80 0.25%
1981 19,846 64 6 0.32%
1982 19,776 48 10 0.24%
End 19,718
Explanation:
a) Data and Calculations:
Baseline starting population = 20,000
Breast Cancer diagnosis at the starting period = 24
Baseline prevalence = 24/20,000 = 0.12%
Time Starting Breast Lost to
Population Cancer Follow-up
Start 20,000 24 0
1980 19,976 50 80
1981 64 6
1982 48 10
End
Time Starting Breast Lost to Cumulative
Population Cancer Follow-up Incidence
Start 20,000 24 0
1980 19,976 50 80 0.25% (50/19,976 * 100)
1981 19,846 64 6 0.32% (64/19,846 * 100)
1982 19,776 48 10 0.24% (48/19,776 * 100)
End 19,718
