The little-known Center for Arts and Public Policy at Wayne State is "the think tank you've never heard of," according to theatre critic Martin Kohn. "We do thinking about stuff that ought to be thought about but people don't have the time," explains theatre professor David Magidson. In a few weeks the center will publish its latest study, which points out that arts and culture form one of Michigan 's key industries. Magidson and Bernard Brock, late co-director of the center, began the study some time ago to look at how the arts have become a tourism magnet for certain cities. As an example, they used Stratford , Ontario . A photo of Magidson accompanies the article.