1. What is the difference between incidence and

prevalence? How are they calculated?

- Incidence is the number of new cases of a disease in a

population during a specified period of time, while

prevalence is the proportion of the population that has the

disease at a given point in time. Incidence is calculated by

dividing the number of new cases by the population at risk

during the time period, while prevalence is calculated by

dividing the number of existing cases by the total

population.

2. What are the types of epidemiologic studies and what are

their advantages and disadvantages?

- The main types of epidemiologic studies are descriptive,

analytical, and experimental. Descriptive studies describe

the distribution and characteristics of a disease or a

population, such as case reports, case series, cross-sectional

studies, and ecological studies. They are useful for

generating hypotheses and identifying patterns, but they

cannot establish causal relationships. Analytical studies

compare groups of people to test hypotheses and identify

associations between exposures and outcomes, such as

cohort studies, case-control studies, and nested case-control

studies. They are useful for estimating relative risks and