Types of research: a synopsis of the major categories and data collection methods.

Different types of research are categorized by reviewing their characteristics and describing how they can be used. Controlled research is experimental in nature and, through a priori planning, allows manipulation of the independent variable so causality can be shown. In ex post facto research, the researcher does not have control of the independent variable and so must infer causality by measuring dependent variables within the framework of independent variables that are already established or whose changes have already taken place. Most applied research in pharmacy is of the ex post facto type. The research questions to be answered will help determine the timing of the measurement of dependent variable (i.e., measure past events or make plans to measure future events), the measuring of the dependent variable (primarily with surveys), and whether time can be used as an independent variable. The effect of time can be determined by repeated measurements over a span of time (longitudinal design) or by measurement of several groups at one point in time (cross-sectional design).