Tim O'Reilly of O'Reilly publishing answered questions on the economics of writing on computer topics. I found this excerpt interesting:
"Your choice of publisher helps [a book be successful]. The clearest lesson from Bookscan (to refer to the data that started this thread) is that the market is consolidating. Fully 80 percent of the market shown by Bookscan (about 65-70 percent of U.S. domestic retail sales, including online accounts) is owned by Pearson, Wiley, O'Reilly, and Microsoft Press, in that order. If you add Osborne and Sybex, you get to 90 percent. (Pearson is a conglomerate owning many individual imprints--AW, PH, Peachpit, Sams, New Riders, Brady, Cisco Press, Adobe Press, Macromedia Press, etc.--so the market looks more diverse than it actually is.) Having been a small publisher who worked my way up over many years, I won't say it [success of a book sold by a small publisher] can't be done. But I think it's a lot harder than it was in the '80s and '90s. In short, being part of an established series at an established publishing house is, unfortunately, very important."
I'm glad my publisher is Pearson's Addison-Wesley!