Pre-filtering vs. post-filtering

Chris Anderson over at The Long Tail blog has some interesting comments on pre vs. post filtering:

In the scarcity-driven markets of limited shelves, screens and channels that we've lived with for most of the past century, entire industries are created around finding and promoting the good stuff. This is what the A&R talent scouts at the record labels do, along with the Hollywood studio executives and store purchasing managers ("Buyers"). In boardrooms around the world, market research teams pour over data that predicts what's likely to sell and thus deserves to win a valuable spot on the shelf, screen or page...and what doesn't.

The key word in the preceding paragraph is "predict". What's different about those kinds of filters and the ones I've been focusing on is that they filter before things get to market. Indeed, their job is to decide what will make it to market and what won't. I call them "pre-filters".

By contrast, the recommendations and search technologies that I'm writing about are "post-filters". They find the best of what's already out there in their area of interest, elevating the good (relevant, interesting, original, etc.) and ignoring or downplaying the bad. When I talk about throwing everything out there and letting the marketplace sort it out, these post-filters are the voice of the marketplace. They channel consumer behavior and amplify it, rather than trying to predict it.

This is an important distinction. In the existing Short Tail markets, where distribution is expensive and shelf space is at a premium, the supply side of the market has to be exceedingly discriminating in what it lets through. These producers, retailers and marketers have made a science of trying to guess what people will want, to improve their odds of picking winners. They don't always guess right--there are surely as many things that deserved to make it market but were overlooked as there are things that made it to market and then flopped--but the survivors get a reputation for some sort of mystical insight into the consumer psyche.

But in Long Tail markets, where distribution is cheap and shelf space is plentiful, the safe bet is to assume that everything is eventually going to be available. The role of filter then shifts from gatekeeper to advisor. Rather than predicting taste, post-filters such as Google measure it. Rather than lumping consumer into pre-determined demographic and psychographic categories, post-filters such as Amazon's custom recommendations treat them like individuals who reveal their likes and dislikes through their behavior. Rather than keeping things off the market, post-filters such as MP3 blogs create a markets for things that are already available by stimulating demand for them.

Both filters are found in the market, of course. Entrepreneurs have to pre-filter their ventures, and then post-filtering by consumers determines success. But I think there are a lot of reasons why post-filtering is better. It lets the market sort things out, rather than trying to guess in advance what it will like. And its more suited to a variety of tastes - because something pre-filtered out is just gone, while there can be an arbitrary number of different post-filters. But you can only do things this way when the cost of making the good is fairly cheap, as with music, writing, etc., so you can just put all your content up and let the post-filters direct people to it.

Blogs are at the top of Anderson's list of post-filters.

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