Psychometric evaluations

Background

The validity of conclusions drawn on the basis of scores from our measures and by different measurement methods is entirely dependent on their quality. If the reliability of our assessments is weakened, or if incorrect or questionable conclusions are drawn, evaluations of treatment effect, alliance, user satisfaction, diagnostics, and individual clinical profiles are at stake. The Norwegian Network for Personality Disorders and its associated quality register islargely based on patient and therapist reported data. Psychometric studies are therefore a significant ongoing research activity associated with this clinical research collaboration.

Financial sources

There is not external funding for this psychometric studies alone. Based on quantitative statistical methods, the psychometric research includes investigation of dimensionality and scale reliability, personality disorder diagnosis, dimensionality of DSM PF criteria, test development, predictive properties, and generalizability/reliability.

Members

• Geir Pedersen (MA,PhD), Senior Researcher and Head of the Network for Personality Disorders, Section for Treatment Research, Department of Research and Innovation, Division of Mental Health and Addiction, Oslo University Hospital.

Chosen publications

1. Müller S, Schroeders U, Bachrach N, Benecke C, Cuevas L, Doering S, Elklit A, Gutiérrez F, Hengartner MP, Hogue TE, Hopwood CJ, Mihura JL, Oltmanns TF, Paap MCS, Pedersen G, Renn D, Ringwald WR, Rossi G, Samuels J, Sharp C, Simonsen E, Skodol AE, Wright AGC, Zimmerman M, Zimmermann J (2025)
   Revisiting the structure of Diagnostic and Statistical Manual of Mental Disorders, fifth edition, Section II personality disorder criteria using individual participant data meta-analysisPersonal Disord. DOI 10.1037/per0000736, PubMed 40705663
2. Paap MCS, Lortz SAJ, Hummelen B, Fjermestad-Noll J, Kvarstein EH, Pedersen G (2025) An Investigation of Longitudinal Measurement Invariance and Item Response Theory Analysis of the LPFS-BF 2.0 in a Large Clinical Norwegian Sample Personal Mental Health, 19 (3), e70032DOI 10.1002/pmh.70032, PubMed 40654158
3. Paap MCS, Pedersen G, Kvarstein E, Hummelen B (2023) Evaluating the Construct Validity of the Norwegian Version of the Level of Personality Functioning Scale - Brief Form 2.0 in a Large Clinical Sample J Pers Assess, 106 (1), 49-59. DOI 10.1080/00223891.2023.2182694, PubMed 36897004
4. Nysaeter TE, Hummelen B, Christensen TB, Eikenaes IU, Selvik SG, Pedersen G, Bender DS, Skodol AE, Paap MCS (2022)
   The Incremental Utility of Criteria A and B of the DSM-5 Alternative Model for Personality Disorders for Predicting DSM-IV/DSM-5 Section II Personality Disorders
   J Pers Assess, 105 (1), 111-120. DOI 10.1080/00223891.2022.2039166, PubMed 35285763
5. Paap, M. C. S., Pedersen, G., Kvarstein, E. H., & Hummelen, B. (2023). Evaluating the Construct Validity of the Norwegian Version of the Level of Personality Functioning Scale - Brief Form 2.0 in A Large Clinical Sample. Journal of Personality Assessment. DOI: 10.1080/00223891.2023.2182694
6. Pedersen G, Kvarstein EH, Wilberg T, Folmo EJ, Burlingame G & Lorentzen S. (2021). The Group Questionnaire (GQ) – Psychometric properties among outpatients with personality disorders. Group Dynamics: Theory, Research, and Practice. http://dx.doi.org/10.1037/gdn0000176 
7. Pedersen G, Norman-Eide E, Eikenæs IU-M, Kvarstein E, Wilberg T (2021). Psychometric evaluation of the Norwegian Toronto Alexithymia Scale (TAS-20) in a multi-site clinical sample of patients with personality disorders and personality problems. Journal ofClinicalPsychology. DOI: 10.1002/jclp.23270
8. Paap MCS, Meijer RR, Cohen-Kettenis PT, Richter-Appelt H, de Cuypere G, Kreukels BPC, Pedersen G, Karterud S, Malt UF & Haraldsen I (2021). Why the factorial structure of the SCL-90-R is unstable: comparing patient groups with different levels of psychological distress using Mokken Scale Analysis. Psychiatry Research, 200(2-3):819-826. DOI: 10.1016/j.psychres.2012.03.012. 
9. Pedersen G, Kvarstein EH & Wilberg T (2017). The Work and Social Adjustment Scale: Psychometric properties and validity among patients with personality disorders and traits. Personality and Mental Health.11, 215–228. DOI: 10.1002/pmh.1382 
10. Paap MCS, Heltne A, Pedersen G, Selvik SG, Frans N, Wilberg T & Hummelen B (2021). More is more: evidence for the incremental value of the SCID-II/SCID-5-PD specific factors over and above a general PD factor. PersonalityDisorders: Theory, Research, and Treatment. https://doi.org/10.1037/per0000426