Sales rank - some observations about how B&N ranks eBooks

[christianbk]

I was curious about why I was seeing some pretty meh titles on the NOOK top 100 list - books that had very little reviews or books from authors I've never heard of - and dug into B&N's sales rank.

I purchased an eBook - The Helm of Midnight - that has limited visibility on the B&N site or when browsing eBooks on a NOOK device. It's part of a promotion - New Year, New Series - and isn't a new release (published in April 2021). It has a total of 14 reviews, with most happening in the first year or so of publishing.

I checked on the eBook's Sales Rank before purchasing. Here's B&N's definition of how they calculate that. Before purchasing, the book's sales rank was 45,211.

I checked the next day and it was 29,803.

That is a difference of 15,408! That's a large jump! I'm thinking that not many people purchased that book on the specific day I did. And if it's one day - one day out of 180 based on B&N's sales rank data calculation - that influenced that jump. Does that mean that B&N books / ebooks don't have a very large "sales tail" of those that purchase less popular books, meaning that people are only buying popular books? Not too surprising, as people buy new releases more than older ones. What about how recent sales are weighted? More on that below.

Here's something I also wondered: Based on the sales rank wording, is the reporting number a general calculation of both physical and eBook sales?

I did a comparison with a high-profile book that went on a deep sale for its eBook - The Way of Kings. This book went on a big discount (down to $1.99) yesterday. It was at 120 sales rank when I checked yesterday; today it is 65.

Seeing as how the sales rank combines both physical and digital, I was curious about how to look at only NOOK sales. Looked at the top 100 bestselling NOOK titles and the Way of Kings was there at #65.

I then looked at the hardcover version's sales rank and that was at 8,854. So B&N doesn't combine physical / digital or even different different physical versions (the paperback was at 2,313).

I'm curious about the line: "More recent sales are weighted more heavily than older sales". I wonder how weighted this may be. It's probably why my book purchase mentioned above made that ebook really jump up the charts (not to anything competitive, but still). I have to wonder if one of those books that I mentioned at the onset that are in the top 100 NOOK eBooks had a handful of people purchase, how many "recent sale" purchases would be needed to have it crack the top 100?

There is a Christmas-themed cowboy romance book that's currently sitting at #7. It's a September 2022 release, priced affordably, and one that seems pretty seasonal (Santa and all). I have to wonder how quickly this title will look to move down the list.