Research method in biostatistics is a basic course for a postgraduate student in Division of Biostatistics, College of Public Health. The course begins with the introduction of study design on experiment and quasi-experiment type. The epidemiological study design in the light of the latter principle is highly highlighted. Different types of validity and reliability are also covered. We also provide sampling methods in the face of survey or selection of study subjects. Finally, the course links these aspects with and statistical methods. The outline for the topic is as follows.