Available online at www.sciencedirect.com Journal of Health Economics 27 (2008) 510–518 Busy physicians Jostein Grytten a,∗ , Rune Sørensen b a Dental Faculty, University of Oslo, P.O. Box 1052, Blindern, 0316 Oslo, Norway b Norwegian School of Management, Sandvika, Norway Received 21 December 2006; received in revised form 16 May 2007; accepted 24 May 2007 Available online 15 January 2008 Abstract Numerous researchers have explored whether general practitioners compensate for a shortage of patients by providing more items of treatment. Empirical testing of this hypothesis often lacks a valid measure of the relevant patient population. In the Norwegian case, researchers have exploited the fact that most patients are registered on a patient list of one general practitioner. However, a significant number of patients move between physicians. We show that physicians with a deficit of patients on the list attract more external patients than those with a surplus of patients on the list. In contrast with previous research, we find no evidence of revenue compensation when consultations with external patients are taken into account. © 2007 Elsevier B.V. All rights reserved. JEL classification: I18 Keywords: Primary physician services; Patient list; Data; Availability 1. Introduction Supplier induced demand continues to haunt the health economy profession. The research question is whether general physicians who are remunerated on a fee-for-service basis, and who have a deficit of patients, compensate for this by providing more services per patient. Two recent studies by Iversen and Lur˚ as (2000) and Iversen (2004) suggest that physicians who report a shortage of patients compensate by providing more services per patient. If this is a valid result, it could suggest that physician competition is imperfect, and that the share of fee-for-service remuneration should be reduced. However, a closer inspection shows that their finding is a statistical artefact. We demonstrate that the Iversen–Lur˚ as result is due to systematic mismeasurement of physicians’ patient populations. The aim of this paper is to demonstrate, how results and conclusions can be influenced by the data that are used and the way in which data are applied. The institutional setting for the study is the general medical practitioner service in Norway. We provide further background for the research question, describe the data we have used, and present the modified empirical results. ∗ Tel.: +47 22 84 03 87; fax: +47 22 84 03 03. E-mail address: josteing@odont.uio.no (J. Grytten). 0167-6296/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jhealeco.2007.05.003