Majid P. Omran recently, published a research article in 2016 about his investigations of structural associations between cognitive beliefs and obsessive-compulsive symptoms. He proposed different models based on measures from the Thought-Action Fusion Scale, the Obsessive Compulsive Inventory - Revised and the obsessive beliefs questionnaire accomplished by a sample of students.

After reading this article, one can notice three main issues regarding (1) the sample, (2) the cognitive model of OCD on which the study is based and (3) the lack of coherence concerning the description of the proposed models of structural associations.

Regarding the limitations of the study, the author correctly mentions that the sample is only composed of regular students, but he does not take into account the possible impact of the male-female ratio on the results. Indeed, the conclusions of the study [1] in a clinical population “indicate a slight female predominance in their sample of OCD patients”. Additionally, they also showed a very “higher frequency of cleaning/washing compulsions in women” in p. 439. Since the sample included double as many women than men, this female predominance could lead to an over estimation of the structural associations between cognitive beliefs and obsessive-compulsive symptoms. As an alternative, the author could analyse the data of men and women separately in order to circumvent the problem mentioned before and additionally to avoid the Simpson’s paradox. This paradox is a “well known statistical phenomenon which the relationship between two variables differs within subgroups compared to that observed for the aggregated data” [2-4].

The theoretical model used by Omran as the basis of his experiment has been an object of controversy. Indeed, Dolan et al. demonstrated that “the traditional view of OCD, which sees the intrusive thoughts as the primary cause of the disorder, has limited validity [2,3]. There are far more people with intrusive thoughts about potential harm than there are patients with OCD” as reported. The authors also suggested that the harm-avoidance behaviours are the actual primary cause for OCD rather than the intrusive thoughts proposed by Omran [3].

The figures that the author presents for the proposed model of structural associations do not support its description. This tends to make it difficult for the reader to comprehend the theoretical basis of this study and the relevance of the findings that it provides.