[1] Department of Medical Informatics,
[2] J2–256,undefined
[3] Academic Medical Center,undefined
[4] P. O. Box 22700,undefined
[5] 1100 DE Amsterdam,undefined
[6] The Netherlands e-mail: n. f.keizer@amc.uva.nl Tel.: + 31-20-5 66 52 05 Fax: + 31-20-6 91 98 40,undefined
[7] Department of Clinical Epidemiology and Biostatistics,undefined
[8] Academic Medical Center,undefined
[9] P. O. Box 22700,undefined
[10] 1100 DE Amsterdam,undefined
[11] The Netherlands,undefined
[12] Intensive Care National Audit & Research Centre,undefined
[13] Tavistock House,undefined
[14] Tavistock Square,undefined
[15] London WC1H 9HR,undefined
[16] UK,undefined