Question

Compare and contrast cyclic trends, secular trends, point epidemics, and clustering.

Answer 1

Cyclic trends, secular trends, point epidemics, and clustering are belongs to the Time Variables.

A. Secular Trends: Gradual changes in the frequency of diseases over long time periods. Female yearly suicide rates are the best example for this.

B. Cyclic Trends: Decreases and increases in the frequency of a disease or other phenomenon over a period of several years or within a year.
Example 1: mortality from pneumonia and influenza (peaks during February).

Example 2: severe weather events in the Atlantic basin.
C. Point Endemics: It may indicate the response of a group of people circumscribed in place to a common source of infection, contamination, or other etiologic factor to which they were exposed almost simultaneously.

D. Clustering: A closely grouped series of events or cases of a disease or other health-related phenomena with well-defined distribution patterns in relation to time or place or both. Clustering can be classified into two types they are temporal clustering (denotes health events that are related in time) and Spatial clustering (indicated cases of disease that occur in a specific geographic region). It may reflect:
-Common exposure to an etiologic agent.
-Chance occurrences.