- Social insurance economics
- Health economics
- Labour economics
- Applied microeconometrics
- Inequity in the use of physician services in Norway before and after introducing patient lists in primary care. International Journal of Equity in Health, 10:25, 2011. (With Karin Monstad)
- Inntektsulikhet og sosiale helseforskjeller. Teorier og empiri. I Haug, K., Kaarbøe, O. og T. Olsen(red): Et helsevesen uten grenser? Cappelen Akademiske Forlag, 2009. (med Karin Monstad)
- Sosial ulikhet i fordelingen av helsetjenester - målemetoder og empiriske funn. I Haug, K., Kaarbøe, O. og T. Olsen (red): Et helsevesen uten grenser? Cappelen Akademiske Forlag, 2009.
- Regulation and pricing of pharmaceuticals: Reference pricing or price cap regulation? European Economic Review.2009,53, 170.185 (With Kurt R. Brekke and Tor Helge Holmås.)
- Return to work after comparing outpatient multidisciplinary treatment programs versus treatment in general practice for patients with chronic widespread pain. European Journal of Pain , 2006, 10, 145-152. (With Skouen, J.S. and E.M.H. Haldorsen)
- Does early intervention with a light mobilization program reduce long term sick leave for low back pain? A three years follow-up study. Spine, 28, 2309-2316, 2003. (with Eli Molde Hagen and Hege R. Eriksen).
- Evaluating social policy by experimental and nonexperimental methods. Scandinavian Journal of Economics, 104, 147-171, 2002. (With Espen Bratberg and Alf Erling Risa).
- Cost-effectiveness of a light multidisciplinary treatment program compared to an extensive multidisciplinary treatment program in cronic low back pain patients on long-term sick leave. A randomized controlled study. Spine, 27, 901-909, 2002. (With J.S. Skouen, E.M.H.Haldorsen and H.Ursin).
- Right treatment to the right patient. Comparison of ordinary treatment, light extensive treatment, and extensive multidisciplinary treatment for long-term sick listed patients with musculoskeletal pain. Pain, 95, 49-63, 2002. (With E.M. Håland Haldorsen, J.S. Skouen, A.E. Risa, K. Kronholm and H. Ursin).
- The performance of sample selection estimators to control for attrition bias. Health Economics, 10, 2001, 385-398.
Equity in health care utilization
- Inequity in the use of physician services in Norway. Changing patterns over time? with Karin Monstad, HEB-working paper no.11/08.
Unequal access to medical care by income in OECD countries. Publications:
- Doorslaer, E. van, C. masseria, X. Koolman and members of the OECD Health Equity Research Group: Income related inequality in the use of medical care in 21 OECD Countries. In OECD, ed. Towards high-performing Health Systems. Policy Studies. Paris, OECD, 2004, 109-165.
- Doorslaer van, E., Masseria, C., Koolman, X. and the OECD Health Equity Research Group: Inequalities in access to medical care by income in OECD countries. Canadian Medical Association Journal, 2006, 174(2),177-83.
Evaluation of the Norwegian retail market for pharmaceuticals. Publications:
- Evaluering av ny apoteklov og indeksprissystemet. Rapport 17, 2003, Rokkansenteret.