Importance of the study protocol in epidemiologic research.

The overall quality of an epidemiologic research project depends on how well both the design and execution phases of the project have been accomplished. The written prestudy protocol, by serving as a bridge between these two project phases, plays a pivotal role in determining the success of the total research effort. The study protocol can contribute to improved observational research in four key areas. Arguments are presented for enhancing the scientific integrity of observational studies and for providing better study documentation, efficiency, and communications, all through careful prestudy planning.