ME patient experiences: Sampling bias limits the external validity of findings.

In a recent paper in Journal of Health Psychology , Kielland et al. present a study with the first objective of documenting how helpful or unhelpful persons with ME perceive common services and interventions. The authors recruited participants by respondent driven sampling, a method that aims to produce estimates that correct for sampling bias. However, we argue that the main assumptions of the method are not met, and that the results of the study thus cannot be generalised to the intended target population.
Competing Interests: Declaration of conflicting interestsThe authors declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: JS declares no conflicting interests. VBBW reports that he has for two decades conducted research in the field of CFS/ME, and that he is chair of the international Collaborative on Fatigue Following Infection (COFFI); VBBW’s research endeavours have been conducted within a biopsychosocial framework.