LOS ANGELES? - Films aimed at parents of youngsters have been so hot this summer that even executives marketing R-rated horror movies must be tempted to work a couple of bars of "We Are Family" into promo spots.

Family films have well outpaced prerelease projections repeatedly since May, and Disney hopes to extend that streak when "The Sorcerer's Apprentice" hits multiplexes Wednesday. Consensus forecasts show the Nicolas Cage family fantasy ringing up more than $30 million during its five-day bow.

Meanwhile, there still is that puzzling matter of why family-film openings are so tough to predict. "The simplest answer is that the tracking doesn't include the young kids themselves," Disney distribution president Chuck Viane said.

Prerelease tracking surveys focus on picture awareness and must-see interest. So asking parents about a kids-targeted release does seem a bit off base.

"The nag factor is what drives those kind of movies," a studio executive mused, a bit indelicately. "The parents might be less inclined than the kids to see a picture, but then the kids pester the parents, and the rest is history."

Studios subscribing to the various movie-tracking services see data on one another's movies, but only companies set to release a kids picture order tracking surveys tailored to that group. Even there, the kids' movie interests tend to be expressed by their parents.

In the end, family moviegoers' impulsive charge on the multiplexes might not show up in tracking polls, but they sure show up in the weekend box office. Such family stampedes also can generate interest among other groups of moviegoers.

"There can be a disconnect in tracking sometimes about how far a picture will reach across all audiences," said Sony distribution president Rory Bruer, whose remake of "The Karate Kid" bowed last month with a much-better-than expected $55.7 million. "There's no doubt that word-of-mouth is important in that aspect."

Word-of-mouth can't be gauged in advance, but positive buzz quickly can morph into outsized box office. Film distribution executives on rival lots used their usual Monday conference calls to discuss why Universal's "Despicable Me" beat projections by such a big margin during the weekend. The animated 3D comedy rang up $56.4 million during its three-day bow, though most industryites expected "Despicable" to debut with $30-35 million.

"People think it was a whole host of things contributing to the big opening," a rival distribution executive said. "You had some fresh-looking characters, funny trailers and a huge boost from running those trailers with other hit family films over the past several weeks."

Still, it was tough to get prospective "Despicable" patrons to focus on the film until just before to its opening, judging from the tepid interest reflected in tracking surveys.

"Tracking could have been distorted by all the other PG movies in the marketplace at the time," Universal distribution president Nikki Rocco said. "The tracking jumped in the last week, but it was very difficult up until then."

The white noise generated by similar releases circulating in the market can distort tracking data, industryites agreed, and summer is chockablock with youth-seeking films. Disney's "Toy Story 3" still is going gangbusters with $339.2 million in sales after four weekends, and "The Karate Kid," boasting a $164.3 million total, also remains in wide release. Even Paramount's "The Last Airbender," which posted a soft second session, well outpaced projections with its $51.8 million bow during the four-day Independence Day frame.

To promote "Apprentice," Disney has been running promo spots during TV networks' kids-show blocks on Saturday mornings. Tracking was slow to pick up, partly because of the youth-market focus on recently released "Eclipse," and even now there remains uncertainty about opening prospects for the pricey Jerry Bruckheimer-produced picture.

"It's just harder to get a handle on what kids are thinking," an industryite said with a shrug. "Tracking surveys are based on what people express in phone and Internet surveys, and you're not going to find the young kids that way."

The only other wide opener set for release this week is an adult-targeting thriller: Warner Bros.' Leonardo DiCaprio starrer "Inception." The Christopher Nolan-directed film opens Friday amid expectations of a $50 million-plus weekend, though in a sense even "Inception" forecasts amount to so much industry guesswork.

Nielsen-NRG, Marketcast and other tracking services stopped giving studio clients specific projections on first-week grosses a couple of years ago, after the sensitive data started circulating around town. A string of embarrassingly wrong projections by the tracking services also might have figured in the policy change.