The development of the research question for a study can be where a lot of research fails. Without a well-defined and specific research question or hypothesis, findings from the research are unlikely to tell us very much. Developing a tightly focused research question or hypothesis defines how and what data is collected and analysed and provides a context for the results. This article, the second in a series of six, focuses on the process of developing a research question or hypothesis from the initial idea through to the final research question, using examples to illustrate the key principles. Approaches to reviewing the literature, including hand searching and the use of electronic sources, are described together with their different strengths and weaknesses. An overview of the deductive and inductive approaches to research are described, as well as the underlying rationale of the null hypothesis and one and two-tailed tests. Finally, issues around the feasibility of the study, including cost, time and relevance, are discussed in relationship to developing the research question or hypothesis.