An extremely important feature of research is the use of appropriate methods. Research involves systematic, controlled, valid and rigorous exploration and description of what is not known, and establishment of associations and causation that permit the accurate prediction of outcomes under a given set of conditions. It also involves identifying gaps in knowledge, verification of what is already known and identification of past errors and limitations. The strength of what you find largely rests on how it was found.
The main function of a research design is to decide, describe, justify and explain how you will find answers to your research questions. The research design sets out the specific details of your enquiry. A research design should include the following: the study design per se and the logistical arrangements that you propose to undertake, the measurement procedures, the sampling strategy, the frame of analysis and the time-frame. (Do not confuse the study design and research design. The study design is just one part of the research design. The research design also includes other parts which constitute the research process.)
For any investigation, the selection of an appropriate research design is crucial in enabling you to arrive at valid findings, comparisons and conclusions. A faulty design results in misleading findings and is therefore tantamount to wasting human and financial resources. In scientific circles, the strength of an empirical investigation is primarily evaluated in the light of the research design adopted. When selecting a research design it is important to ensure that it is valid, workable and manageable. Chapter 7 provides details about the research design most commonly used in quantitative and qualitative research.
There is an enormous variety of study designs (Chapter 8) and you need to be acquainted with some of the most common ones both in quantitative and qualitative approaches. The chapter does not separately describe study designs for the mixed methods approach as it primarily uses those which are either quantitative or qualitative. Select or develop the design that is most suited to your study. You must have strong reasons for selecting a particular design; you must be able to justify your selection; and you should be aware of its strengths, weaknesses and limitations. In addition, you will need to explain the logistical details needed to implement the suggested design.