Seminal · article · 1998

Comparison of Rasch and Summated Rating Scales Constructed from SF-36 Physical Functioning Items in Seven Countries

Anastasia E. Raczek; John E. Ware; Jakob Bue Bjørner; Barbara Gandek; Stephen M. Haley; Neil K. Aaronson; Giovanni Apolone; Per Bech; John Brazier; Monika Bullinger; Marianne Sullivan

Rasch models for polytomous items were used to assess the scaling assumptions and compare item response patterns in the 10-item SF-36 physical functioning scale (PF-10) for general population respondents in Denmark, Germany, Italy, the Netherlands, Sweden, the United Kingdom, and the United States. The Rasch model of physical functioning developed in the United States was compared to models for other countries, and each country was compared to a multinational composite. Strong scale congruence across the seven countries was demonstrated; items that varied between countries and from the composite may reflect unique cultural response patterns or differences in translation. Scoring algorithms based on the Rasch model for each country were superior to the current Likert scoring in tests of relative validity (RV) in discriminating among age groups in all countries. In relation to the Likert P...