Barnes and Noble Book Store vs Amazon Stocking

I've spent some time over the past month looking into comparisons between Barnes & Noble book stores and Amazon in terms of their core stocking. In the brick-and-mortar book store world, title stocking is also known as "modeling." To use it in a sentence, Barnes & Noble models two copies of title X across the chain, meaning the computerized ordering model tries to keep two copies in inventory every physical location. I've never heard modeling used in conjunction with Amazon's predictive ordering system, but they obviously strive to stock titles that are selling well for 24 hour shipping, and do a pretty good job at it.

What got me thinking about the differences between their title offerings is a discussion I've been involved with about the Long Tail phenomena on Amazon. It seems to me that before you can really get into a discussion about the tail on a beast, you have to decide what the beast is. For the sake of comparing apples with apples, it would be wonderful if Barnes & Noble book stores stocked a subset of Amazon's title catalog that corresponded with the top 100,000 or so books. Unfortunately, that's not the case. Stocking at Barnes & Noble book stores varies with the size of the store, between 60,000 and 200,000 titles, "of which 50,000 are common to all stores." However, we have no way of knowing what percentage of the 50,000 common titles are books published by Barnes & Noble themselves.

Now the situation is further complicated by the fact that Amazon does not stock many of the current titles published by Barnes & Noble in their store, and many of those titles that they do list were added by Marketplace Vendors. Some of these titles actually sell quite well in Barnes & Noble book stores, the "Step by Step" color illustrated computer series comes to mind. Even when some these books are made available on Amazon, they don't end up in the body of the beast due to limited availability.

On the other hand, there are many new titles stocked for 24 hour shipping and selling in the top 100,000 at Amazon which aren't stocked in Barnes & Noble book stores (and often never were). In addition, Amazon has a large but unquantified number of out-of-print books selling in the top 100,000, either older editions of new books, titles from failed publishers, or titles whose sales didn't justify a new print run for the publisher, and for which all the demand is now through Amazon.

This leaves us with two beasts, and I'm not really sure how different they are. Their bodies are certainly similar enough to be recognizable, especially the head (say the top 1,000 or so titles), but after that, some titles modeled in every Barnes & Noble book store only appear in the Long Tail at Amazon, if they catalog them at all. By the same token, some of the titles in the body of the beast at Amazon can't even be ordered by physical Barnes & Noble book stores because they are out-of-print. If I had a way of quantifying how big these non-overlapping inventories were, I could venture a comment on how important they are to the overall Long Tail picture, but aside from asserting that they are positive percentage values, I don't have a good method for estimating them.