Professor emeritus Klaas Sijtsma

The seminar will take place in seminar room Jordgubbe (Strawberry), House 4, 3rd floor, Albano.

Professor Sijtsma will also act as the opponent on Erik Forsberg's dissertation, Friday 4 October. Read more

Organizer of this seminar is the Division of Work and Organizational Psychology.

Contact: Associate Professor Anders Sjöberg

Abstract

Since the introduction of latent variable models such as item response theory models and factor models (structural equation modeling), latent variables have become favorite for representing abilities and traits and differentiating individuals with respect to these attributes. However, in the practice of reporting test results to examinees and others concerned such as parents, teachers, employers, and therapists, sum scores and test scores that are transformations of sum scores (standardized scores, percentiles, IQ-scores, scores on educational tests) are often used because of their simplicity and intuitive appeal: They are simply easier to understand and interpret than scores on latent variables such as log odds, and therefore have greater potential for communication.

I will demonstrate that for standard testing, sum scores and their transformations are fully acceptable. Actually—and few people including psychometricians know this—item response theory provides the theoretical justification for the practical use of the simple sum score. I will discuss situations in which the sum score should be preferred to the latent variable and illuminate the opposite situations where the latent variable is superior and must be preferred to the sum score. Both have merits and drawbacks, often in different situations. Thus, they complement and strengthen each other rather than compete.

Recommended reading

Sijtsma, K., Ellis, J. L., & Borsboom, D. (2024). Recognize the value of the sum score, psychometrics’ greatest accomplishment. Psychometrika, 89, 84-117. doi:10.1007/s11336-024-09964-7

About the General seminars in psychology

This series of seminars is a collaboration between the six research divisions at the Department of Psychology. Local, national and international researchers are invited to speak of current research subjects.

The seminars are held on Wednesdays at 14:00–15:00 onsite in Albano and/or online in Zoom. Extra seminars can also be held on other weekdays or hours, among these the so called half-time seminars in the Doctoral Program in Psychology.