At the Author Earning website, there is an another statistical study about publishing, comparing Amazon with four other outlets and showing the results of different channels through these outlets. A side issue arose for me in reading the report. They said a large percent of indie published works do not have ISBN numbers assigned and therefore miss getting included in industry standard reporting. The conclusion drawn is that ISBN numbers may be becoming irrelevant.
Of what use are these numbers? And can one purchase legitimate numbers outside of Bowker?