ABSTRACT
24The first step in defining your research question is to decide what theoretical constructs to be used as explanatory and response variables. Once you have determined what effect you want to examine, you must determine the population in which you want to examine it. The first criterion you must have is that the studies need to measure both the explanatory and response variables defining your effect and provide an estimate of their relationship. You should expect that your list of inclusion and exclusion criteria will change during the course of your analysis. The first and most important decision in preparing a review is to determine its focus. This is best done by asking clearly framed questions. It is often helpful to consider the types of people that are of interest in two steps. First, define the diseases or conditions that are of interest. Second, identify the population and setting of interest. The next key component of a well-formulated question is to specify the interventions that are of interest. The third key component of a well-formulated question is the delineation of particular outcomes that are of interest. Determining the scope of a review question is a decision dependent upon multiple factors. Narrow questions may result in spurious or biased conclusions and may not be generalizable. As broad questions may be addressed by large sets of heterogeneous studies, the synthesis and interpretation of data may be particularly challenging.
