Final answer:
To get disease rates, divide the number of cases of a disease by the number of at-risk people. Multiply the rates by a factor for better understanding. To find the percentage of students who are carriers of a disease, divide the numerator by the denominator and multiply by 100. In cohort studies, risk ratios can be calculated by comparing the incidence of a health-related event in exposed and unexposed groups.
Step-by-step explanation:
To get disease rates, we need to divide by an appropriate denominator. This is done to account for the number of at-risk people in a population during a specific time period. For example, to calculate the prevalence rate, we divide the number of cases of a disease in a population by the number of at-risk people. To express the rates in a more understandable manner, they are often multiplied by a factor of 100, 1,000, or even 100,000, so that the rates are expressed in terms of people per 100, 1,000, or 100,000 individuals respectively.
To find the percent of students who are carriers of a disease, divide the numerator by the denominator and multiply by 100. This gives us the proportion or percentage of the population affected with the disease.
Additionally, in cohort studies, epidemiologists may calculate risk ratios to assess the association between a factor and a disease or health outcome. The risk ratio is obtained by dividing the incidence of the health-related event in a group exposed to a condition by the incidence of the same event in a group not exposed.