PMC6423000_01
Three different outcome or process measures for patient James (retrieved from; reprinted with permission): (A) the BDI from baseline to 1-year follow-up; (B) cortisol stress hormone measures from baseline to 1-year follow-up; (C) medical health care costs from years prior to 2 years after treatment.
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F4
However, James's cortisol levels show a different image of long-term success: whereas his stress levels indeed reduced over the course of treatment, at the second follow-up his stress hormone levels were about twice as high as baseline (Figure 4A,B). A second alternative source of information on the treatment success in James's case could be the information on his medical health costs (Figure 4C).
The validity of the research process entails both the internal validity of the design and the epistemic validity of the function of the design in a researcher's epistemic endeavor.
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Especially in the era of EBT, this epistemic pragmatism is a very relevant question for psychotherapy research: All research designs are chosen in function of some epistemic context that makes it relevant and important to conduct that particular study (Figure 5). As becomes clear from Figure 5, neither the way that a concept is operationalized nor the function of the process of operationalization in the overall epistemic endeavor of the researcher are (necessarily) covered by the test validity of the instrument that is used.