ABSTRACT

Descriptive studies beyond clinical case reporting, give us a better understanding of how a problem looks. Analytical studies or etiological research deal with causes. Experimental studies expose subjects to preventive or therapeutic maneuvers in order to assess how these solutions work. A longitudinal study can follow a single group, but obtaining a desirable picture of height and weight in the children will take nine years. A semi-longitudinal study, however, requires only three years of follow-up. Research studies are a written report of an organized experience. The quality and scope of studies that produce evidence is inherent to their nature. A clearly formulated question at the beginning of a study will determine the success of the study. Good evidence does not guarantee that the results of the study can be successfully put into the practice. Evidence must be evaluated in ways that are different from an assessment of cause–effect relationships in different types of studies.