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Behavioural Science

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Research Methodology

The Downside of the Glorious RCTs

Martin Metzmacher
· 1 min read

RCTs are great and every empirical scientist loves them. Everyone? No there is a small village in the south of France…Well to be honest I believe that RCT’s are just a hype. Of course they were great in reducing a lot of statistical problems and have helped psychology to become a “respected science” and earn a place in between mother philosophy and father medicine. In the retrospective the big advances in psychology have all been made by individuals that used single case designs (Freud, Piaget, Skinner…). Why is that the cause?

As much as RCTs can tell us about the statistical differences between groups they are not very good at telling us what the processes at hand are. RCT are also often conducted in special settings and with high treatment fidelity and lots of resources, something the “real world” often does not have to offer. All of this makes it complicated to derive any practical treatment value from them. If there is some practical value to it, one will have to search for it by reading the whole article and giving a few hours of thought to it.

Scientists write for scientists (or rather they write to please their peer-reviewers). This is a mindset quite far from the therapist that lives in a world in which all the factors that are excluded from RCT (for obvious reasons), like: economical and technical problems, comorbidity, lack of resources, converge and interact with each other.

The mindset of the therapist often does not entail thoughts of simple causality of X influencing Y, but of a multidimensional system in which all factors interact with each other. Thus the information value derived from RCTs might seem huge for the scientists, but low for the therapist that needs support in his treatment decisions.

Research Methodology1 min read

What is Effect Size?

Effect size is a parametric test, belonging to the GLM family that allows to compare the size of an effect between two groups (or for that matter two conditions in one group). The test can be used in all kinds of research designs (experimental and non-experimental) that employ different kind of measurements or/and manipulations. Given […]

Research Methodology1 min read

Why the CBCL’s Inter-rater Reliability is poor at the Item and Syndrome level

There seem to be no obvious methodological or statistical issues that could account for the poor inter-rater reliability. Embregts argues that informants might have a different view on presence and severity of behavioral problems depending on the frequency and quality of interaction they have with the client (“biased” data). Secondly both judges might have different […]

Research Methodology1 min read

The Probabilistic Nature of Behavioural Phenotypes

The probabilistic nature of behavioural phenotypes proclaims that people with a specific syndrome will have a heightened probability to exhibit specific behavior or developmental pathways that are different to others, who do not have the specific syndrome. The advantage of probabilistic nature of the construct is that it can account for exceptions and it is […]