Those who have known me for awhile know that I use a complex system known as Deuce Factor to rate movie trailers (aka "previews").
More recently, I watched two films in a row (National Treasure: Book of Secrets and Indiana Jones and the Kingdom of the Crystal Skull) in which, at some point or another, I found myself scouring the edge of the screens hoping to find a glimpse of an alien, a predator, or an alien fighting a predator. This is usually not a good sign. The film Predator 2 had a neat little aside in which there was an Alien skeleton on the Predator ship, and while that was a nice little bit of prop usage to imply more of a back story than the film itself cared to provide in its main narrative, my overall feeling is that if the audience is scouring the edges for those sorts of things, that's usually an indication that the film itself isn't working, and the director knows he/she has to fill the screen with easter eggs to make the audience happy.
So I've decided to introduce a cousin to "Deuce Factor"--the Predator Scale. The Predator Scale scores movies rather than trailers. A film's Predator Scale score is determined by your answer to a simple question. Would the film be better, worse, or no different, if a Predator made a cameo appearance at any point during the screening? A film that would be improved by the appearance of a Predator scores +1 on the Predator scale. (Examples would be the two mentioned above, as well as Jurassic Park III, Alvin and the Chipmunks, Into the Wild, and There Will Be Blood.) A film that would be made worse by the appearance of a Predator scores a -1 on the Predator scale. (Hint--It's like golf, lower is better.) Examples might be Lars and the Real Girl, Honeydripper, or High Fidelity. A Predator Push indicates the film would be no better nor worse for the appearance of a Predator--Star Wars: The Phantom Menace (heck, I haven't scoured the crowd shots, there may have been one for all I know), The Jane Austen Book Club, or Iron Man.
I think--though I haven't really worked this out yet--that the most common types of films to earn a +1 would be ones that are lacking in entertainment value or (here's where Indy fits in) need some sort of signal to the audience that the film is not taking itself too seriously and neither should we.
A push may even be a worse score as it could indicate (among other things) a film that is already so far gone that the appearance of a Predator wouldn't make it any more ridiculous or so pretentious that a Predator appearance would seem just cynical as opposed to self-effacing or fun.