An understanding of statistical concepts is important for biomedical researchers. Statistics and probability are the scientific basis for dealing with sources of variation inherent in most biologic processes. This paper provides an introduction to the statistical framework that is fundamental to scientific methods of inquiry. Topics covered include the role of statistics, hierarchy of evidence, reliability and bias, sample size and power, random samples and random allocation, hypothesis testing, estimation, statistical inference, and publication bias. Future papers will focus on specific statistical techniques commonly used in biomedical research.