If you live in the city’s south end near Woodroffe Avenue and Fallowfield Road, you may want to stock up on a little extra candy this Halloween.

Same story if you live off of Donald Street in the Overbook neighbourhood.

Those areas have among the highest ratios of individual dwellings to what Statistics Canada defines as children of “prime trick-or-treating age,” according to a Canada-wide map that’s the brainchild of Jens von Bergmann, a 42-year-old software developer from Vancouver with a Ph.D. in mathematics.

“I think just the general idea of which areas will see more foot traffic, which will see less — I think that’s useful information for people,” said von Bergmann, who co-created the map with his colleague Alejandro Cervantes.

Statistics Canada defines “prime trick-or-treating age” as between five and 14 years old. Von Bergmann decided to take their data and divide it by the number of private dwellings in a census tract, and then colour-code that resulting ratio on the map — with darker areas representing denser neighbourhoods.

In the census tract south of Donald between Pére Charlebois Avenue and Frances Street, for example, there were 65 children between the ages of five and nine listed in the 2011 census, 55 children between 10 and 14 years old, and 134 private dwellings.

According to von Bergmann’s data, the ratio of children-to-dwellings in that census tract is approximately 0.9, one of the highest in Ottawa. So if you live there, there’s a good chance a young ghoul or witch will be showing up on your doorstep Saturday night.

Census data from 2011

The most recent census data von Bergmann had access to was from 2011, but he says that shouldn’t matter much.

“The age distribution overall doesn’t change that much over the course of four years,” he said. “Birth rates are pretty constant.”

Von Bergmann calls the trick-or-treating map “more or less a gimmick” and says he’s used census data for more serious endeavours — like creating data-driven maps that delve into issues like housing prices and commuting costs.

He acknowledges, though, that they’re not as popular as his Halloween map.

“They’ve seen, comparatively, much less interest,” he says. “But I guess that’s the nature of things.”

One variable not accounted for

That said, there’s one variable von Bergmann’s map doesn’t account for — the fact that some neighbourhoods see more foot traffic Halloween night because there are economic incentives to travel there.

When Keheng Zhai and his brother were of prime trick-or-treating age, they’d leave Barrhaven and head over to wealthy Rockcliffe Park for the best Halloween treats.

“People there are richer!” laughed Zhai, 21. They’ll give more candy, and they’re more generous”