A research method is a general framework guiding a research project. Different methods can be used to tackle different questions. Research design is a specific outline detailing how your chosen method will be applied to answer a particular research question.
Research methods are generalized and established ways of approaching research questions (e.g., qualitative vs. quantitative methods). Not all methods can be applied to all research questions, so the choice of method is limited by the area of research that you wish to explore.
Research design involves determining how your chosen method will be applied to answer your research question. The design of your study can be thought of as a blueprint detailing what will be done and how this will be accomplished. Key aspects of research design include: research methodology; participant/sample collection and assignment (if different conditions are being explored); and data collection procedures and instruments.
Choice of research methods and design should be thought of as a reciprocal process extending well into your study. For example, it may arise over the course of your study that there is a flaw in the design. Changing the design of the study may lead to the choice (or addition) of a different method which, in turn, may lead to subsequent changes in the design to accommodate the new method(s).
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