This new series of articles about research is aimed at those people who have not undertaken formal education in research appreciation but who wish to understand the concepts underpinning research design and the interpretation of findings. The series will start with a description of what research is and the different philosophies which influence study design. As the series progresses, it will consider levels of evidence and discuss factors to be considered when designing a research study and interpreting the findings, such as validity, reliability and sample selection.