Question

Incidence Rate Question with the answer (not sure how denominator & nominator have been founded, please can explain the below answer)
The denominator consists of the population at risk (i.e., those who are at risk for contracting the disease).
Example: Calculate the incidence rate of postmenopausal breast cancer in the IWHS. The population at risk in this example would not include women who were still premenopausal (n = 569), women who had had their breasts surgically removed (n = 1,870), and women with a previous diagnosis of cancer (n = 2,293).

Thus, the denominator is 37,105 women. After eight years of follow-up, 1,085 cases were identified through the State Health Registry. The incidence rate is therefore 1,085/37,105 per eight years. To express this rate per 100,000 population: Divide 1,085 by 37,105 (answer: 0.02924). This is the rate
over an eight-year period. For the annual rate, divide this number by eight years (answer: 0.003655) and multiply by 100,000.
Answer: 365.5 cases of postmenopausal breast cancer per 100,000 women per year.

formula incident rate=( number of new cases over a time period / total population at risk during the same time period )* 100,00

Answer 1