Study of time, place and person is called as -
Descriptive epidemiology (Descriptive studies) 

Descriptive studies are usually the first phase of an epidemiological investigation.
These studies are concerned with observing the distribution of disease and identifying the characteristics with which the disease in question seems to be associated.

Procedures in Descriptive Studies
1. Defining the population to be studied
2. Defining the disease under study
3.  Describing the disease by

Time
Place
Person

4. Measurement of disease
5. Comparing with known indices
6. Formulation of an etiological hypothesis

Descriptive studies are used to formulate etiological hypothesis.
Experimental epidemiology
Analytical epidemiology
Descriptive epidemiology
Randomized controlled trial