Amazon Rank: How Related Is It To Author Earnings?

I've always wondered this. Let's say your book has an Amazon Sales Rank of 50,000, and lets say it stays there for a month. What does this mean in terms of how much money an author could expect their book to make?

Is there a correlation between sales and Amazon Rank?

Passive Guy brought up this topic today in one of his rare posts. He posed three questions:

Question #1: Is this [Amazon Best Sellers Rank] a fair way of evaluating how well an ebook-only or mostly-ebook publisher performs for authors?

Question #2: While we’re discussing Amazon Best Sellers Rank, has anyone seen any credible discussions concerning how sales rank translates into dollars for indie authors? If you’re at 20,000 with a $2.99 ebook, are you making $500 per month from that book? Or is Amazon’s algorithm too volatile to make it a useful gauge of the dollars coming in the door?

Question #3: Everybody knows that lots of ebooks have experienced sales spikes immediately after Christmas as new ereaders and tablets are packed with ebooks. What about other sales patterns? For example, do sales go up on the weekend when many people have more leisure time to read?

PG hasn’t seen any analyses of sales rank that address these kinds of questions.

He doesn’t want to trigger obsessive-compulsive behavior centered on your KDP dashboard, but would be interested in whatever tribal knowledge his readers might have about sales rank.

The rest of PG's article is here: Amazon Sales Rank vs. Author Earnings.

Cheers.