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Nowadays people know the price of everything and the value of nothing.

—Oscar Wilde

*Mr. Ketterman's Case

I know I need to read the articles about Mr. Ketterman's care, but I just don't know where to start. I often read just the Abstract or the Introduction and the Conclusion because all that information in the Methods and Results just confuses me. But, I know I'm missing a lot of important information! (See Appendix for Mr. Ketterman's health history.)

Having found evidence that relates most closely to a clinical question, the next step in the evidence based practice (EBP) process requires the careful reading and critiquing of the evidence. But this is perhaps the most daunting task facing clinicians who wish to practice in an evidence based manner—determining whether evidence found in the literature can be of value to their patients. As the sophistication of physical therapy research increases, the task of evaluating any research report for its accuracy and truthfulness becomes more challenging. After all, the evidence can only be of value to your patient if it is derived from a valid study. Validity, used here to mean trustworthiness, is an essential characteristic of any individual study. The more the results of a study can be trusted, the greater its validity in helping to make an informed clinical decision. An understanding of some of the methodological and analytical standards for conducting valid, high-quality clinical research experiments is a good starting point to build one's critical appraisal abilities. In this chapter we will focus on understanding the elements of good research. Chapters 13, 14, 15, 16 will then apply the principles of good research practice to the various types of evidence, ranging from single studies to systems (Fig. 12-1).1

Figure 12-1

Sources of Information About Evidence. (From DiCenso A, Bayley L, Haynes RB. Accessing pre-appraised evidence: Fine-tuning the 5S model into a 6S model. Evid Based Nurs. 2009;12:99–101.)

It is not the intention of this text to provide direction for researchers, nor to be a full source of all the details of research design and management that a clinician might find interesting. Rather, we have attempted to identify the essential elements that should be considered in assessing the literature. Because there are many such elements and you may wish to focus on them specifically when reviewing articles, we provide an overview of what will be covered in this chapter (Box 12.1).


We will compare two large categories of research designs, experimental research designs and observational research designs. The research design is selected by the investigator based on the research question of interest. As you have seen in Chapter 10, questions may relate to selecting the best examinations in order to determine ...

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