How do Hollywood’s biggest stars stack up? It’s all in the numbers.

Who knew Hollywood popularity was such a science? In 1963, a Manhasset, New York–based firm called Marketing Evaluations developed a numerical strategy for rating a performer’s appeal, familiarity, and likability. The resulting “Q Score” system has remained a valuable resource for production studios, network programmers, and advertisers for determining which stars are most marketable. In this business -- with hundreds of millions of dollars riding on a single movie or campaign --a likable star equals a bankable one.

“Nielsen [ratings] rate behavior. What Nielsen doesn’t say is how much people like what theyare watching,” says Henry Schafer, Marketing Evaluations’ executive vice president. “Our data is used to help with decision making in hiring a specific talent for a specific job.”

Every six months, the company surveys a revolving panel of 1,800 American consumers on their recognition of and fondness for actors, athletes, and other celebrities. Their Q Scores can be as high as a perfect 100, though Bill Cosby has been the closest to ever reaching it, with a one timescore of 71. The lowest to date has been Kevin Federline, at a negative 81. Who currently tops the list? Schafer gives us a sneak peek.