All of the following are analytical epidemiological studies except -

Ans. is `d' i.e., Field trialAnalytical epidemiology (Analytical study) o Analytical studies are the second major type of epidemiological studies (after descriptive studies).o It contrast to descriptive studies that look at entire population, in analytic studies, the subject of interest is the individual within the population (except in ecological study).o The object is not to formulate, but to test hypothesis.o There are four major types of analytical observational studies -i) Case control study Longitudinal studiesii) Coho studyiii) Cross sectional studyiv) Ecological studyo Simplest form of observational Study --> Cross-sectional Studyo Most preferable observational/analytic Study design --> Coho Studyo Least preferable observational/analytic study design ----> Ecological Study.