PHILADELPHIA (CBS) – Boosters of big events like this month’s Philadelphia International Festival of the Arts are fond of saying they’ll pump X-millions of dollars into the economy.  It’s not just guesswork.

It’s both an art and science, according to Professor Daniel Funk of Temple’s School of Tourism and Hospitality Management.  The science (math, really) is crunching numbers.  The art is which numbers and which kind of crunch.

For example: who is a tourist?

“Some rules say if you travel, say, 50 miles and stay overnight, that makes you a tourist,” Funk said.

So their hotel, meals, entertainment and shopping count toward a ripple effect, like a pebble in a pond.  A bigger pebble from far away is best.

“If you come to Philadelphia from Paris or Frankfurt, you’re going international so you spend more, so obviously events that attract international people, they spend more than domestic tourists from California, let’s say.”

Professor Funk says there’s also a cost to tourism, so you have to look at the net benefit.

Reported by John Ostapkovich, KYW Newsradio 1060