Determining Ontario's supply and requirements for ophthalmologists in 2000 and 2005: 1. Methods.
BACKGROUND
We performed a study to determine the supply of and requirements for ophthalmologists in Ontario in 2000 and 2005. In this paper we describe our methods.


METHODS
The future supply of ophthalmologists was estimated by means of iterative multiple regression analysis using the baseline number of ophthalmologists, the number of ophthalmology residents and the numbers of ophthalmologists entering and exiting the workforce between 1989 and 2004. Data were obtained from the Ontario Physician Human Resource Data Centre, Statistics Canada, the Ontario Ministry of Finance and residency program directors of Ontario universities. We calculated requirements using four models. The physician:population ratio method used an ophthalmologist:population ratio (1:29,650) proposed by the Royal College of Physicians and Surgeons of Canada and Statistics Canada population projections for 2000 and 2005. The utilization-based, substitution and needs-based models used Ontario Health Insurance Plan data for 1995. The supply and requirements are expressed as full-time equivalents, defined as the average number of minutes worked by ophthalmologists in 1995. The 401 ophthalmologists practising in Ontario in 1995 accounted for 452 full-time equivalents.


CONCLUSIONS
Incorporating the results of several requirement models increases the reliability and acceptability of estimates of physician workforce requirements.
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