So how did Streep win that Oscar?

LOS ANGELES — Shortly after Meryl Streep beat out Viola Davis for the lead actress Academy Award on Sunday night, Disney/abc Television President Anne Sweeney bumped into Octavia Spencer, Davis’ co-star in The Help.

Sweeney was overheard in an elevator leaving the awards telling Spencer that she was “upset. I feel bad for Viola,” Sweeney said. Spencer, who had just won an Oscar herself for supporting actress, asked Sweeney how she thought the upset had happened. “I have my theories,” the executive said, without elaborating.

The Streep question was on many people’s minds. While her turn as Margaret Thatcher in The Iron Lady had earned her several honors leading up to the Academy Awards, including a Golden Globe and a BAFTA, Davis seemed to have Oscar momentum on her side after she won the Screen Actors Guild Award. (Because actors constitute the largest branch of the motion picture academy, which hands out the Oscars, SAG awards are seen as strong bellwethers.)

Other factors also lay in Davis’ favor: The Help was a box-office hit and received more critical praise than Iron Lady. And although Streep is the most-nominated actress in Oscar history, she had been on a serious losing streak, having struck out with academy voters on 12 consecutive previous nominations.

One popular explanation centered on the awards campaign run by Harvey Weinstein, whose company distributed Iron Lady. One academy member, who asked not to be named because he did not want to jeopardize business relationships, said that the film’s backers had emphasized to members how Streep, 62, was practically due a trophy after so many years of going unrecognized. A Weinstein consultant did not respond to a request for comment on the company’s strategy.

But perhaps equally as important may have been the fact that Streep was playing a character based on a real person while Davis, as the fictional maid Aibileen Clark, was not.

In three of the last four races when a woman playing a well-known public figure was nominated for lead actress, she won: Marion Cotillard did it playing Edith Piaf in 2007’s La Vie en Rose; Helen Mirren turned the trick incarnating Queen Elizabeth II in 2006’s The Queen; and Reese Witherspoon pulled it off tackling the role of June Carter in 2005’s Walk the Line.

The lone exception was a partial one: It came in 2010, when Sandra Bullock won for her role in The Blind Side. Bullock was playing the reallife Leigh Anne Tuohy, but she defeated an actress playing a better known personality — coincidentally Streep, playing Julia Child in Julie & Julia.

Voters may lean toward actors playing well-known figures because they have a frame of reference by which to judge the performance. “Real-people imitations rank high on [the academy’s] register,” said veteran awards consultant Tony Angellotti.

At the same time, an ostensibly helpful factor — repeat nominations — can sometimes work against a performer. Many pundits believed Streep lost to Bullock because it was Bullock’s first nomination, and her candidacy felt to some voters like a rare opportunity to give her a trophy.

This year, though, Streep came out on top, a result that even seemed to surprise her.

“Frankly, I understand Streep fatigue,” the actress told reporters backstage right after she accepted her statuette. “And it shocked me that it didn’t override this tonight.”