When Walt Disney Co. said the third "Pirates of the Caribbean" set a box-office record for a movie opening, Sony Corp. responded less than two hours later saying not so — its "Spider-Man 3" is the champ.

The unusual public clash between two of Hollywood's biggest studios last week illustrates how they try to create a buzz that will draw audiences. The dispute also casts a light on box-office accounting procedures that allow companies to cherry-pick statistics to support their claims.

"Saying it's the biggest movie is a way to generate business," said Bill Mechanic, former head of News Corp.'s Twentieth Century Fox studio. The numbers the movie companies tout "are just extrapolations," he said. "It's a complicated thing to get your hands around."

Studios may be more inclined to spin the numbers because of the rising expense of movie-making. "Pirates of the Caribbean: At World's End" cost $300 million to make, estimated Box Office Mojo LLC, a company that tracks the industry. "Spider-Man 3" cost $258 million.

That would make "Pirates" the most expensive film ever, exceeding the inflation-adjusted $290.2 million cost of 1963's "Cleopatra," according to December 2005 rankings by Forbes Magazine. "Spider-Man 3" would be fourth, following No. 3 "Superman Returns," distributed last year.

In the "Spider-Man" and "Pirates" argument, Disney and Sony may both be right because of the way studios get and parse their box-office numbers.

Sony Pictures said in a May 7 media release that "Spider-Man 3" had set a global "weekend" record. Weekend in this case covered six days, because the film opened on Tuesday, May 1, in Tokyo. Receipts from a film's first three days, usually Friday through Sunday, are the normal U.S. benchmark.

Burbank, California-based Disney, the second-largest U.S. media company, responded in kind, saying on May 29 that over its first six days, "Pirates" brought in more than "Spider-Man."

Sony promptly issued an e-mail challenging Disney's numbers, saying they included "irregularities" such as receipts from previews in "at least" two countries. Disney was essentially counting seven days of revenue, Sony said in the statement.

"Claiming it's a six-day record when that's been shoveled in is a little gray," Mark Zucker, Sony's head of international distribution, said in an interview.

Disney stands by its numbers. The company's box-office reporting "has been completely and thoroughly accurate and transparent," Mark Zoradi, Disney's distribution and marketing chief, said in an e-mailed statement.

"We appreciate that other distributors want to protect their claims but there is simply no merit to their assertion," Zoradi said.

The companies have leeway in picking revenue figures as well as the days included. For about 80 percent of U.S. theaters, distributors receive numbers from data companies Nielsen EDI and Rentrak Corp. Studios are free to use the higher number.

The Nielsen and Rentrak figures aren't made public. Sallie Olmsted, a spokeswoman for Rentrak, said the company wouldn't comment. Tim Ganser, vice president for international sales for Los Angeles-based Nielsen, also declined comment.

The studios estimate the remaining 20 percent of the U.S. total based on data they receive from Nielsen and Rentrak.

The numbers become even more debatable and easier to massage in the growing overseas market. Last year, 63 percent of the $25.8 billion in worldwide box-office sales came from outside the U.S. and Canada.

"Pirates," shown in 102 countries, took in $229 million in the U.S. and $635.5 million worldwide as of June 6, according to Box Office Mojo. "Spider-Man 3" garnered $320.6 million in the U.S. and $847.2 million globally.

Coverage by Rentrak and Nielsen varies from country to country outside the U.S., Sony's Zucker said. About 99 percent of theaters in the U.K. and Australia provide results to the firms; in smaller countries such as Bulgaria, studios call theaters individually for results.

Release dates also vary, complicating comparisons. In the U.S., movies typically open on Fridays, while in Japan they debut on Saturdays, Zucker said.