Essentials of Biostatistics. 2. Desings of Medical studies

Abstract

It may have been realized from the previous article(l) that empiricism is the backbone of medical knowledge. Studies in various forms are constantly carried out to acquire better and wider knowledge. To effectively detect a trend, generally a series of subjects is studied. Empiricism requires that the steps to study such a series should essentially consist of preparation of a protocol, collection of observations, and their collation and analysis. The tool which really architects the study is the protocol. It delineates the procedures to be followed from the beginning to the end - the inclusion and the exclusion criteria for the subjects, the method of selection, the number of subjects to be studied of various types, the methods to be adopted for collection of observations including modes of measurement, and the plan of analysis. Proper justification including the ethics is given for the procedures to be followed at each step. A protocol is considered complete when the background of the study explaining the need is also described along with a short review of the literature appraising the existing status. It also contains a clear statement on the broad and specific objectives of the study. Much of the planning depends on these objectives. We give a brief overview of various types of designs in Section 2.1 and give details of each in the subsequent sections.