"Count what is countable. Measure what is measureable. What is not measureable, make measureable." -- Galileo

Monday, December 31, 2007

The Plone Reference Library and Amazon Statistics

I was poking around in Amazon.com recently and realized that it had some numbers that would be worth kicking around. Plone holds up well in the "number of books about it" category (6) for open-source CMS, although Drupal comes close with 4 and SharePoint blows everyone away with 48.

In terms of Amazon sales rank, Aspeli's book is doing well at 40,410. By comparison, SharePoint for Dummies comes in at 17,382 and Pro Drupal Development at an astonishing 6,168. The full set of data from Amazon, looking at number of reviews, customer ratings, and sales rank are:

Title Author Sales Rank
Professional Plone Development Aspeli 40,410
Building Websites with Plone Cooper 93,139
Definitive Guide to Plone McKay 139,560
Content Management with Plone: Handbook for Authors and Editors Lotze,Theune 213,164
Plone Live Pelletier, Shariff 455,539
Plone Content Management Essentials Meloni 584,584

Title Reviews Rating
Professional Plone Development 5 5.0
Building Websites with Plone 7 3.5
Definitive Guide to Plone 15 4.0
Content Management with Plone: Handbook for Authors and Editors 0 ---
Plone Live 5 5.0
Plone Content Management Essentials 8 3.5

By way of comparison, here are the numbers for Drupal:

Title Author Sales Rank
Pro Drupal Development VanDyk, Westgate 6,168
Drupal: Creating Blogs… Websites Mercer 34,996
Building Online Communities Douglass, et al. 138,071
Practical Drupal Mansfield 534,402

Title Reviews Rating
Pro Drupal Development 36 5.0
Drupal: Creating Blogs… Websites 16 3.5
Building Online Communities 26 3.5
Practical Drupal 0

Interestingly, sales rankings bounce around hourly. "Pro Drupal Development" had a 3,648 ranking last night and this morning it had fallen to 6,168. A couple Plone titles changed places overnight.

Amazon restricts raw sales data to authors and publishers only, so what are we to do with these mysterious "sales rank" numbers? I suggest a figure of merit (FOM) that is one over the sales rank (larger sales rank number means lower sales). One finds that the sum of all Plone sales rank FOMs is 1/6 that of the Drupal total sales rank FOM. This may mean that roughly six times as many Drupal books are being sold as Plone books on Amazon. I should mention that 81% of Drupal's figure comes from a single title, "Pro Drupal Development."

But some caveats are due. "Definitive Guide to Plone" is available free on the Web and "Plone Live" is best obtained by online subscription. These would certainly depress the Amazon numbers. Also, one should take into account how much online documentation is available--better free documentation would mean less need for that reference book on the shelf.

One last statistical pernambulation: take the number of reviews and multiply it times the average rating in number of stars. Plone totals 162.5 and Drupal comes in with 327. Over half of Drupal's total comes from VanDyk and Westgate's book

The oddest statistics were the category rankings that Amazon had. Meloni's book is the last place Plone title and yet it ranks #2 in Content Management. Meanwhile, "Practical Drupal" clocks in a #11 even though it has a slightly higher overall sales rating.

What, if anything, can the Plone community do about this? First, support your authors--buy their books. Second, review their books, rank them, and perhaps most importantly, tag them so that they pop up high in the category searches, especially "Content Management."

Amazon is a wealth of objective data. I'll come back to this data set and look at other CMS at a later date as well as reviewing how Plone texts are moving in the statistics.

Have a Happy and Prosperous New Year!

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