Artilce Review: Psychotherapies

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Hi,

Another interesting article! Have you read it yet? It is a somewhat complicated article.

Let's take a closer look at each question, then, which you can draw on for your final copy. I also provided the page numbers for easy referencing, so you could provide more detail when/if necessary.

1. What is the purpose of the study?

The purpose of the study is to test the Dodo bird conjecture: that when psychotherapies intended to be therapeutic are compared, the true differences among all such treatments are zero (p. 2).

2. What is the problem, theory, and/or research context that gave rise to the study.

The authors build the case for the need for their study based on the problem as they see it (p. 1-3).
Briefly, the problem is that the previous meta-analysis studies of the Dodo bird conjecture were flawed in a number of important ways, which resulted in many confounding variables due to the nature of the study design that impacted the reliability of the results e.g. studies did not compare two or more studies directly, treatments were classified into general types and studies were included that may not have been intended to be therapeutic (bona fide). This gave rise to the present study (see characteristics of this meta-analysis where the authors address these problems in testing the Dodo bird conjecture p. 3, second column, near the end).

3. What is the research question(s) and major hypotheses.

Are the bona fide psychotherapies equally effective, as proposed by the Dodo bird conjecture?

"The fundamental hypothesis to test in this meta-analysis is whether the overall differential effect of bona fide psychotherapies is zero. However, the authors point out the since the effect size is arbitrary, it cannot be used to directly test that the true effect size for comparison is zero" (see further explanation on p. 6, toward bottom of the first column).

Ho: The true difference is zero (e.g. meaning that the bona fide psychotherapies are equally effective (p. 2)).

Ha: The true difference is NOT equal to zero (e.g. meaning that the bona fide psychotherapies are NOT equally effective- see graph on the bottom of p. 4).

Other hypotheses and predictions mentioned in the article:

Hypothesis:

(a) We predict that treatments that fall into the same class are more similar to each other than treatments in different classes (p. 4, bottom of the first column).

(b) If the dodo bird conjecture is false, in vivo exposure and imaginal exposure would be expected to produce smaller differences than would treatments that are very dissimilar, such as vivo exposure and insight oriented treatment.

(c) If the Dodo bird conjecture is false, there should be a negative relation between similarity and size of the effect. Because date of publication and similarity of treatment might be confounded, the relations of effect size to date and similarity are tested simultaneously (see p. 4)

4. What are the methods used: e.g., subjects, measures, & procedures.

There are no human participants, per se, but instead the data from the studies on bona fide psychotherapies act in this way, as participants. That is, instead of collecting data about psychotherapies from human subjects, the data is collected from previous studies that fit the operational definition of bona fide psychotherapies as proposed by the authors.

Method:

(a) General analytic strategies: used to test the Dodo bird conjecture: Goal was to locate studies that compared ...