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

Tuesday, October 13, 2009

More Stats from Amazon

Its been another quarter and its time for a look at Amazon sales ranks for Plone books. From the graph above, you can see that some texts are bouncing around while others are trending steadily. I can't really explain the sales improvement for many titles last July (remember "dips" are actually good in terms of sales rank). The new titles have lost ground somewhat after the initial flurry of sales, but no one has gone over a cliff.

Without doing any further analysis (hey, its 3 a.m.), it looks like there's a cluster of books in the low to mid hundreds of thousands and another cluster above 800,000. We'll have to wait until December to see if this pattern is persistent.

My own behavior might explain some of this from an anecdotal point of view. At my day job we've just been going through the upgrade from 2.5 to 3.1 (don't ask). At any rate, its time to dust off my notes from Joel Burton's class last year and buy the Plone 3 texts for the rest of the staff. Not being an early adopter in the Plone upgrade process, we've held off on upgrading our technical library until now. I suspect others are in the same boat and this sort of lag will continue to drive Plone 3 book sales for some time.

I read with interest a piece from Morris Rosenthal where he's basically reverse engineered the sales ranks. Despite that, Amazon numbers are amazingly fluid and trending them is tricky, especially for those with ranks below 20,000. He's got some interesting graphs and an insightful writeup. In simple terms, Morris states the obvious:
Read an average rank of 1,000 to mean you have a seriously successful title, an average rank of 10,000 to mean your doing pretty good for a book that's no bestseller, an average rank of 100,000 to mean it's not going to contribute significantly to your income, and an average rank of 1,000,000 to mean you need to take a break from checking sales ranks.
Of course, these are Amazon numbers, so remember that online sales (Pelletier & Shariff) and direct sales from our friends at Packt (many of the others) will have a significant impact. Its also nice to note that Plone top sellers have ratings of 4.5 to 5.0.

By way of comparison, Drupal has four titles with sales ranks under 20,000. Unfortunately, they all have ratings of 4.5 or less. Joomla has three titles ranked under 50,000. Their ratings are 4.0 or less. WordPress has four books ranked under 20,000 ranked variously between 3.5 and 5.0.


Martin Aspeli said...

The comment sounds about right: I couldn't make a living from writing Plone books (but it's a nice bit of supplemental income).

Mark said...

Love your Galileo quote.

BTW, Are you manually collecting your sales rank metrics? If so, you might want to check out Metric Junkie. You can track up to 10 books for free.


Schlepp said...

Mark, I also use Sales Rank Express -- http://www.salesrankexpress.com

Mark said...

Sales Rank Express is an excellent Amazon Sales Rank checker.

For long term analysis you may want to supplement your research with a sales rank tracker such as Metric Junkie which collects sales ranks for you over time and plots them on a graph revealing hidden details (like the number of actual sales and market share) that would otherwise go unnoticed.

Since you are plotting data over time it appeared that a tracker may be just what the doctor ordered. Wasn't sure if you were aware that trackers exist.