Practice-based Research in (allied) healthcare

1 Research competence for a professional context

Levels of evidence Within the field of scientific literature, there exists a wide variety of types of studies with different research designs . What type of research design best suits your needs depends largely on your research question. Furthermore, practical concerns (e.g. time, money, the number of available participants) or ethical considerations factor into your choice of research design. Some research designs generally lead to stronger, more reliable ( reliable means reproducible or repeatable) and more valid evidence than others. To make the strength of evidence based on the research design more "transparent”, a hierarchy of different research designs and the levels of evidence they generally produce has been created. For intervention studies , this hierarchy has been visualised in the form of a pyramid based on each design’s level of evidence , as shown in Figure 1.4.

Systematic review (meta-analysis) Randomised controlled trials (RCTs)

Cohort studies

Case-control studies (patient-control research)

Cross-sectional studies

Case series, case reports

Experts’ ideas/opinions

Pyramid of the levels of evidence (intervention research)

Figure 1.4

Note that it would be false to assume that researchers who choose a research design with a lower level of evidence necessarily conduct bad research. However, it does tell you something about the strength of the evidence that the study in question produces. Besides choosing the right research design, there are myriad pitfalls during the exact performance of your research that can negatively affect the value of your findings. Specific (methodological) criteria have been drawn up for various research designs that you can use to assess the strengths and weaknesses of a study yourself.

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