IF SHELBURNE MAYOR Ed Crewson is right, Dufferin continues to need an additional 15 family physicians.

His figure is based on population and the theory that an area becomes under-serviced when the ratio is less than one doctor for every 1,380 residents.

We cannot argue with the mayor's calculation, nor can we suggest that the theory is wrong, but the figures may be too much of a generality to be considered reliable.

It may very well be that within a vast sampling of the population, a single general practitioner can service 1,380 patients.

Dufferin County is not, however, a vast sampling. When it comes down to the particulars of the needs of fewer than 60,000 persons - as opposed to the general needs on average of a national 30-plus million - one has to factor in the special needs of a percentage of the population that's normally considered to be "at risk."

Suppose for a moment that are two Dufferins, each with the same population but one with four chronic-care facilities and a median age of 50 and the other with none and a relatively youthful general population.

The one with the youthful population and no residents qualifying for chronic care might be assumed to be relatively healthy and thus might require only one doctor for, say, every 2,000 persons.

But the other county, with a relatively elderly population and many residents requiring chronic care might well require one doctor for every 760 residents.

In that example, the "average" would hold true. But, on statistical averages alone, one of the counties would be over-serviced while the other would be under-serviced if they acquired doctors based on their statistical needs alone.

That is a simplistic illustration to demonstrate that demographics is as important to a survey of needs as is raw population figures.

One has to consider that Shelburne has three "at risk" facilities within its 5,500 population, based on a combination of age and health - Dufferin Oaks, Shelburne Residence, and Shelburne hospital. Orangeville also has such facilities, but they form a tiny portion of the town's nearly 30,000 population.

We would not suggest that more physicians are not needed in Orangeville to serve the south of the county. But there needs to be a concerted effort to find doctors willing to meet the evident needs - on site - of the relatively larger "at risk" population in Shelburne.

Meanwhile, one might hope that the current situation will be relieved by some of the Orangeville doctors agreeing to do something that was supposed to have happened long ago - agree to spend a portion of each week in the currently empty clinic facilities in Shelburne.