* Sales ranks can jump around A LOT. These numbers will have changed by the time you read this blog post! If you want a quick and easy way to compare books, check out Titlez.com (if anyone knows a way to get data average over a longer period, please let me know!)
** Studies have shown that the first few reviews of a book are always higher than later ones. A good rule of thumb is to consider the number of reviews (i.e. consistency) along with the actual average rating.
*** These books are either ones targeted at programming/development, or ones focused on a specific subject within Joomla. As such, one needs to be careful comparing their rank to the other, more general titles.