The crudest type of editing involves removing the bad stuff and leaving the good, but any sort of real editing in the service of storytelling is much more than that. Of course there are articles, books, classes and entire careers built on mastering the Art of Editing, but there are some simple, clear and useful metrics you can look at to dissect the craft as well. One of the easiest to analyze is the length of the shots. Sure, it might be a tad nerdy or even obsessive, but I'm also convinced that you can learn something basic about the pace and rhythm of a film this way.

Think about the pace of the editing between the modern action flick The Bourne Supremacy (2004) and Jean Renoir's rendition of Madame Bovary (1933). You can measure this pace in terms of the average number of shots-per-minute or by analyzing the average shot length. The rate or pace of cuts in a modern action film can be frighteningly frenetic. Take a guess what the Average Shot Length (ASL) is in a film like The Bourne Supremacy. Would you believe 2.4 seconds? That's over 2,500 edits in the 100-minute long movie. Seems like that would be almost unwatchable, doesn't it? Madame Bovary positively lingers at 22.8 seconds per shot, but neither of these films are at the extremes.

Of course, the entire Jason Borne film doesn't consist of absolutely periodic cuts every 2.4 seconds and the pace changes throughout the story. For example, the ASL of the 1959 version of Ben Hur is about 8 seconds overall, but our hearts start racing as the editing pace increases and the drums pound as the rowers in the galleon hit "Battle speed!" and the ASL shortens to 1.2 seconds for that scene.

You might think that ASL and edit pace is an academic issue and not something that producers think about when making a movie and, to some extent, you are right, but I have often worked on projects where we spec a cuts-per-minute (or edits-per-minute) goal during pre-production planning. It's not that every cut automatically adds energy and interest, but keeping things lively can be important and it's easy to lose sight of the forest for the trees, especially when you are sitting in an edit bay looking a frames. So, for example, when I create a How To video, I am consciously thinking about 8-12 edits per minute (ASL of rough 5-8 seconds), but even eight seems a little slow. You don't want to arbitrarily toss in cuts just for the sake of hitting your ASL figure, but you do want to at least pay attention to the pace.

How do you know what the pace should be? Well, like for everything else: Watch TV and movies! Find programs that you want to emulate and watch them closely. Most simply, you can just use a pen, paper and a stopwatch to measure out the edits-per-minute or you can get as elaborate as breaking out the laptop and using Yuri Tsivian's Cinematics tool to measure the overall ASL. At a minimum, hop over to the Cinemetrics Website and at least glance at the database to get an idea of the pace of some films.

References:
* Cinemetrics.lv