NEW YORK -- Serena Williams insists she moved on quickly after her bad night two years ago at the U.S. Open.
Some of her fans, it seems, moved on as well -- without her.
Williams' N-Score, a measure of her name recognition, popularity and a number of other factors, went down significantly in the year after she made news by screaming and shaking her racket at a line judge who called a foot fault on her late in the 2009 semifinal against Kim Clijsters.
On a scale that starts at zero and can reach into the high triple digits, Williams' score fell from 213 to 131 in the 12 months following her outburst, a referendum of sorts on her semiserious statement earlier this week that, "I got really popular. A lot of people were telling me they thought I was super cool, that they never saw me so intense."
The survey, conducted by Nielsen and the E-Poll marketing research group, has lately looked at the tennis star's popularity every September.
In last year's ratings, Williams' "positive appeal" -- people who say they like her or like her "a lot" -- fell from 42 percent to 38 percent. The number of people who disliked her doubled from 3 to 6 percent. By comparison, Roger Federer has a "positive appeal" of 52 percent and Maria Sharapova is at 57 percent.
The number of people who knew who Williams was fell from 48 to 42 percent -- continuing a decline from her peak of 57 percent recognition in 2005. Williams, however, did not play in last year's U.S. Open, which concluded shortly before the survey was conducted.
"Serena's got incredible awareness but the positive appeal figures have never really been that high," said Stephen Master, vice president of the sports group at Nielsen. "She's always been a bit polarizing, not as much of a fan favorite."
The N-Score is a marketing tool that identifies a celebrity's name and face recognition but also categorizes their popularity into age groups, specific likes and dislikes of a company's potential customers and 46 characteristics such as "down to earth," "confident," "intelligent" and "creepy." It combines all that to create a single "N-Score" number.
When conducting the polls, Nielsen and E-Poll use a representative sample of 1,100 people, asking half if they've heard of a certain person's name and showing that person's picture to the other half to see if they recognize the face.
"In many instances, the awareness level is somewhat similar for a name and a face," Master said. "Sometimes there are differences, like in the case of Michael Vick, whose name has been out there a lot but whose face isn't as well known because he wears a helmet when he plays.
"Then, we get down to appeal. We ask about personality characteristics. This is where companies appreciate the level of specificity and detail we've got on each person," Master said.
Though Williams' numbers have waned a bit, she can still take heart: She and her sister, Venus (169), have higher overall N-Scores than Sharapova (43), and tennis players are, by far, the most popular female athletes across the board.
The Williamses are also in rare company in that they have better N-Scores than a number of retired tennis players, who tend to score high. Andre Agassi is at 115, while Billie Jean King, Chris Evert and Martina Navratilova rate in the 70s and 80s, Master said. Federer got a 57. John McEnroe scored a 45.
"If he wins the U.S. Open, a big tournament in New York, I'd expect the number to go up," Master said of Djokovic.
Master said that any number -- even a one -- is a good sign because it means a personality had enough recognition to be in the survey. Also, the ratings are exponential, not linear -- in other words, the difference between one and 100 is greater than the difference between 100 and 200.
About 70 percent of the stars whose names are in the poll score between one and 30 points -- a "starter" in N-Score lingo. Only 4 percent are in the so-called Hall of Fame category, people with scores of 200 or higher. Serena's 131 would rate her a "superstar."
Master said Tiger Woods once reached into the 800s but now rates a 93, Michael Jordan is in the 600s and X-Games star Shaun White scores a 209.