Analyzing Effectiveness of Long-term Psychodynamic Psychotherapy
- Brett D. Thombs, PhD brett.thombs@mcgill.ca;
- Marielle Bassel, BA;
- Lisa R. Jewett, BADepartment of PsychiatryMcGill UniversityMontreal, Quebec, Canada
Since this article does not have an abstract, we have provided the first 150 words of the full text.
- KEYWORDS:
- DATA INTERPRETATION, STATISTICAL
- META-ANALYSIS AS TOPIC
- PSYCHOTHERAPY
- PUBLICATION BIAS
- RANDOMIZED CONTROLLED TRIALS AS TOPIC
- TIME FACTORS
To the Editor: Drs Leichsenring and Rabung1 reported that long-term psychodynamic psychotherapy (LTPP) is more effective than shorter forms of psychotherapy for complex mental disorders based on a between-group effect size of 1.8 from 7 comparative trials that they meta-analyzed. The authors did not indicate that they were concerned about this and other surprisingly large effect sizes they reported.
Between-group effect sizes can be presented as group differences in terms of standard deviations or as point biserial correlations between group (eg, LTPP vs shorter-term therapies) and treatment effect. They are equivalent and convertible using a formula or tables.2 The authors, however, apparently erroneously calculated within-group pre-post effect sizes and point biserial correlations between group and within-group effect sizes, which is altogether different. It seems that they converted these correlations between group and within-group pre-post effect sizes to produce deviation-based effect sizes that do not appear reasonable.
As a …
