Final answer:
There are three types of calculations used to describe and compare measures of disease occurrence: ratio, proportions, and rates. A ratio compares the number of cases in one group to another, while proportions compare the number of cases to the total population. Rates take into account time and represent the number of cases per unit of time.
Step-by-step explanation:
There are three types of calculations used to describe and compare measures of disease occurrence: ratio, proportions, and rates.
1. Ratio:
A ratio is a comparison of two numbers or quantities. In the context of disease occurrence, a ratio compares the number of cases of a health-related event in one group to the number of cases in another group. For example, if there are 50 cases of a disease in a group of 100 people and 25 cases in a group of 50 people, the ratio would be 50/25 or 2/1.
2. Proportions:
A proportion is a type of ratio that compares a part to the whole. In the context of disease occurrence, a proportion compares the number of cases to the total population. For example, if there are 100 cases of a disease in a population of 1000 people, the proportion would be 100/1000 or 0.1 (or 10%).
3. Rates:
A rate is a type of proportion that takes into account time. It represents the number of cases of a disease per unit of time. For example, if there are 10 new cases of a disease in a population of 1000 people in one year, the rate would be 10/1000 per year or 0.01 (or 1%).