In the world of celebrity, it's simply called Q. And you've either got it or you don't.

Julia Roberts and Tom Hanks have it. Martha Stewart and Woody Allen are, sadly, close to Q-less.

Q is a nebulous, but extremely powerful force. In Tinseltown, it's a popularity litmus test on par (or maybe beating) the Nielsen ratings. If you've got above-average Q, you're bankable, usually beautiful and you get the best roles.

Story continues below advertisement

The Q factor -- Q stands for qualitative -- is an indicator of star power, a measure of both how familiar and likable the public finds a particular actor or celebrity. It's the Dow Jones index of Hollywood.

The world's reigning Q guru, Steven Levitt, says Q defies a neat definition. Nevertheless, his company Marketing Evaluations/TVQ Inc., has studiously measured TVQ and PerformerQ for close to 40 years. The best explanation he offers is that stars with Q "don't seem phony or fake.

"They don't seem artificial," Levitt tries to explain. "They're not made-up, disingenuous, they're not egotistical. The ones with the highest ratings often have a sense of humour and are self-deprecating." (Think Robin Williams or Michael J. Fox.) "You see the real people behind the roles they play," he adds.

Unlike the Nielsen numbers that measure how many people are watching a show, Q scores measure whether viewers like what they see. It goes without saying that Q scores are avidly sought by advertisers, programmers, networks, studios and public-relations firms.

Twice a year, Levitt's Manhasset, N.Y.-based research firm publishes its Q scores, ranking some 1,700 performers from 21 different categories, including movie and TV stars, musicians, comedians, TV announcers, models and authors. (Politicians, royalty and religious figures aren't ranked.) The firm conducts 1,800 individual interviews and uses data compiled from a consumer base of 50,000 households nationwide in the United States. (There is no Q survey of the Canadian public.)

The TVQ portion of the survey polls a national panel of respondents aged 6 and older to see, first, if they're familiar with certain personalities or television shows, and second, how they feel about them -- are they "one of my favourites," "very good," "good," "fair," "poor" or "never seen or heard of before?"

The Q score is then calculated based on how widely known someone is and how many of those familiar with that person or program identify him, her or it as being among their favourites.

Story continues below advertisement

As a result, a personality who is recognizable but not much liked (say, Donald Trump) might have a lower Q score than someone less widely known who elicits a more positive reaction (such as The Sopranos' mob boss played by James Gandolfini or co-stars William Peterson and Marg Helgenberg on CBS's hit crime show, CSI: Crime Scene Investigation).

Levitt's clients are a Who's Who of entertainment and media elite. His research is so in demand that the company has steadily branched into other Q areas. For example, Cartoon Q was added in 1983, Product Q in 1988, Sports Q in 1990, Kids' Product Q in 1996 and Cable Q in 1998.

There is even a category called Dead Q (performers of the past), with notable names like John Candy, Joe diMaggio and Albert Einstein ranking near the top of that list.

So who in this wonky business has above-grade Q? In his heyday as Cliff Huxtable, Bill Cosby had better Q than anyone in the business (he still holds the record at 71 out of 100).

Cosby's rating has slipped in the past decade, but the comedian's still up there with the current Q kings and queens, including Hanks and Roberts, Mel Gibson, Bart Simpson, Scooby-Doo and Wayne Gretzky.

Q technicians say Mickey Mouse has good Q, as does Tiger Woods, and George Foreman. Some in movie and TV land believe actors are either born with Q, or they're not. Levitt says it's possible to bolster your Q. The key, he adds, is for personalities to "earn their likability" and that depends "how they present themselves to the public in their different roles. Q ratings change as performers get new roles, make career changes, do stupid things, annoy audiences."

Story continues below advertisement

Case in point, Levitt says, is O. J. Simpson -- a one-time stellar Q man who is now pathetically low on the Q scale. ("Murder charges have a way of doing that," Levitt adds. "The Bronco ride didn't help either.")

TV talk-show host Rosie O'Donnell has also seen her Q quota tumble in recent months. A year ago, O'Donnell was a 21. She's since fallen to a 16. The Q pundits predict that the release of her autobiography (in which she revealed that she is a lesbian), combined with her decision to quit her show, were major negatives for O'Donnell's blue-collar, U.S.-heartland audience.

Others with dismal Q include Michael Jackson (excessive facial reconstruction apparently freaks people out), Woody Allen (he should have stuck with Mia and left Soon-Yi alone) and Martha Stewart. "Maybe people resent her, or maybe she just gets on their nerves," says Levitt. "They buy her stuff, but they don't necessarily like her that much." It's safe to assume that the Q of the dominatrix of domesticity will only decline further as the New York Stock Exchange waves ta-ta to her this week in the wake of the ImClone stock scandal.

Audrey Hepburn had it. Jennifer Love Hewitt, who was dumb enough to try recreating that long-ago mystique in a TV movie, doesn't. Marlon Brando, svelte and powerful in A Streetcar Named Desire, lumpy and wizened in The Godfather, always had it. Jackie Gleason practically embodied it. And the Tony Soprano character played by Gandolfini, who has a gut like a beer barrel and the pug nose of a prizefighter, has Q in spades (even when he tries to whack his mother).

The ones with high Q are the television producer's dream and a casting agent's easiest call. Under Q scores, breast size and biceps don't matter as much as the intangibles, things like humility, genuineness and warmth.

Toronto-based film and television producer Jay Firestone says Q, for him, boils down to one thing: energy. "Trying to pigeonhole Q into a neat little definition," muses Firestone, "is like asking someone, 'How do you explain love at first sight?' There are no rules to it."

Story continues below advertisement

Firestone, whose company Fireworks Entertainment is behind TV series such as La Femme Nikita, Andromeda and Mutant X, says there is no set formula for producers who are searching for stars who might possess that mysterious alchemy called Q on camera. "You have to realize that a lot of these people look a lot different on television than they do in real life," he says. For instance, he believes Nikita co-stars Peta Wilson and Roy Dupuis had Q, but they brought buckets more of it out in each other. "As soon as they read together, we knew they had that indefinable something that would click with audiences," Firestone adds.

"I was talking the other day about this very thing with [ Shawshank Redemption director Frank Darabont]and he told me that he determines Q by asking the actor to talk about the part." For Q to exist, the director told him, the actor has to be himself and the role has to come naturally. Celebrities with Q, whether on TV or the big screen, make it look easy. Simple. Natural.

In theory, the highest Q rating would be 100, but Levitt said average appeal is pegged at 20. If a performer scores 28 and above, that's pretty good "for mainstream popularity," he adds.

Today's top-rated movie star Hanks has a Q score of 56, Levitt says, followed by the usual suspects Mel Gibson, Tom Cruise, Harrison Ford, Sean Connery, Robin Williams, Bill Cosby and Julia Roberts, whose score has risen since she nabbed her Oscar. The toothy actress now is the woman with the highest Q on the general list.

Levitt also ranks shows with good Q. "Starting in September/October of last year, CSI was near the top of the list of programs with high Q scores," explains Levitt. "It was above ER, Friends and Everybody Loves Raymond. The Nielsen ratings would never reflect the fact [so quickly]that it just broke through and into the public conscience. We told CBS it had a hit on its hands."

The same sort of thing happened with Fox's 24, the real-time drama starring Kiefer Sutherland. Soon after its premiere last fall, Levitt's company recorded relatively low levels of familiarity, but it was a overwhelming favourite with many viewers, which meant it had potential.

Story continues below advertisement

" CSI and 24 are shows that, without the Q rating, might have been cancelled before the end of the first season," says Levitt. "If networks went only by Nielsen, audiences would never have seen Cheers, Family Ties, Hill Street Blues, or All in the Family. Q scores basically say, 'Wait, wait, wait.' It tells the network executives that these shows are worth promoting because the audience feels very strongly about the programs."

Q can be a maddening formula to try to measure up against for actors. Take Canadian Gloria Slade, best known for her stint as Barb Stephens, wife of Marty on the CTV drama Traders, who believes Q -- at the basic level -- is the actor's ability to draw viewers. She's not sure if she's got Q or not.

"That's a good question," she says. "Being part of Traders (a show with TVQ) definitely helped my career along. It gave casting directors a chance to see my work on an ongoing basis. And now my agent and I don't have to work as hard just to get an audition. And sometimes roles are just offered to me. God, I love that! But do I have Q? Some. Not enough. I need more."

In an ideal world, Q scores wouldn't be necessary. Producers would fill roles based on merit or gut instinct, not a one-letter research tool. Not long ago, O'Donnell apparently griped about producers relying on Q scores to dictate which guests she could book on her show.

But Q is now an accepted, even respected way of deciphering popularity or bankability in Hollywood. With seven-figure-plus production and advertising dollars at stake, it's no wonder executives increasing rely on Q scores to help them find the right person in the right role at the right time.

Anne Marie La Traverse, executive producer of this season's new CTV drama The Eleventh Hour, has spent the past six months trying to find actors with that unique magnetism that will help propel her fledgling show into a must-see on the dial. She says her team agonized over the which actors to pick to play the investigative journalists and on-air personalities that will capture the audience's imagination and keep them coming back.

Story continues below advertisement

"The thing with casting is it's very instinctive. And to dissect it into pieces is hard. But we were after stars with Q," adds La Traverse. "And I think what we look for, first and foremost, is good actors who make the dialogue feel real. So you never feel that it's written.

"Second, we wanted actors who are authentic in their part. We needed two on-air personalities with weight and presence. We chose Sonja Smits [ Traders and Street Legal]and Sir John Neville [who has played everything from Baron Munchausen to the well-manicured man in The X-Files] Those two actors have Q. They have each played characters in other programs that have become part of people's lives in a way. They leave an impression." The series also stars Shawn Doyle, Waneta Storms, Peter MacNeill, Tanya Reid and Jeff Seymour.

La Traverse says Neville and Smits are in the same Q league as the Due South Mountie Paul Gross -- Canadian actors all who come across as "authentic.

"Q is an ingredient that is very difficult to describe," she continues. "It may be something that people are simply born with. I guess it's a kind of energy, or magic that comes alive in front of a camera.

"People with Q just have that extra little bit of sparkle." The world according to Q

Not to be confused with IQ, the Q Factor -- as its known in TV and movie circles -- is that uncanny ability that actors may (or may not) have to click spectacularly with audiences. Q -- which stands for qualitative -- is basically a measure of a person or thing's popularity (or potential popularity). Here's a list of some stars who, for whatever reason, we find so damn likable. And a few we apparently can't stand. High Q: Tom Hanks; Robin Williams; Mel Gibson; Steven Spielberg; Denzel Washington; The Sopranos' James Gandolfini; CSI: Crime Scene Investigation's co-stars, William Peterson and Marg Helgenberger; Julia Roberts; Glenn Close; Meryl Streep; the Harlem Globe Trotters; Joe diMaggio; Homer and Bart Simpson; Scooby-Doo; Mickey Mouse; Robert Urich; the Olsen twins; George Foreman; Tiger Woods; Bill Cosby; Audrey Hepburn; Marlon Brando; Jackie Gleason; Andy Griffith; Carroll O'Connor; Oprah Winfrey; Elvis; Albert Einstein; and Michael Jordan. Some current TV shows with High Q: CSI: Crime Scene Investigation; ER; Friends; Everybody Loves Raymond; The Bernie Mac Show; 24; My Wife and Kids; The District; and Law & Order. Some Canadians with Healthy Q: John Candy; Wayne Gretzky; Eric McCormack; Celine Dion; Michael J. Fox; and Anne Murray.

Folks with Low Q: Martha Stewart; Michael Jackson; Woody Allen; Kathie Lee Gifford; Donald Trump; and Jennifer Love Hewitt.