II. Definition
- Number of new disease cases per population at risk
- High Incidence implies high disease occurrence
 - Low Incidence implies low disease occurrence
 
 - Measured over a given time interval
 
III. Usage
- Determine probability of developing a specific disease
 - Used to detect etiologic factors
 
IV. References
- Hennekens (1987) Epidemiology Medicine, p.54-98