The Principles of Biomedical Scientific Writing: Materials and Methods.

The materials and methods (M&M) section is the heart of a scientific paper and is subject to initial screening of the editor to decide whether the manuscript should be sent for external review. If the M&M section of a scientific paper be considered as a recipe, its ingredients would be who, what, when, where, how, and why. M&M should effectively respond to the study question/hypothesis using the following basic elements including materials, study design, study population/subjects or animals, methods of measurements/assessments, and statistical analysis. A well-organized M&M permits other scientists to evaluate the study findings and repeat the experiments. Although there are several disciplinary differences in the M&M, similar dos and don'ts may be considered to organize a well-written M&M. Briefly, authors need to provide clear-cut, adequate, and detailed information in the M&M section. In this review, the structure, the principles, and the most common recommendations for writing the M&M section are provided, both in general and study-specific; these could help authors effectively prepare the M&M section of a scientific biomedical manuscript.