Why Does NovelRank Underestimate Sales for Popular Books?

Every once in a while, I get an email from an author with Kindle Direct Publishing (KDP) access who wonders why their numbers are different between NovelRank and KDP. First and foremost, let me say that if you have KDP access for your titles, that is the most accurate source of sales data. Secondly, remember that NovelRank estimates sales based off of sales rank, which is also a data point provided by Amazon, a priority system for ranking books based upon their sales. This makes any estimates vulnerable to many variables, and I wanted to provide some additional info for folks.

One final note before I start listing things: I created NovelRank as a resource that allows authors to spend less time reloading webpages, spend more time writing, and get a feel for the effectiveness of marketing campaigns by seeing hourly and daily fluctuations. It’s hard to communicate this throughout the website, and a few folks have taken to disliking NovelRank strictly based on sales estimates. It hurts a little, but I try and focus on those who are benefiting from the service.

Causes for Underestimation:

The better the sales rank, the less variation. Since sales estimates are based upon changes in sales rank, this reduced variation is the first source of underestimation.
Furthermore, when sales rank is really good (low number), improving estimates usually means adding arbitrary +X amounts to sales estimates. I try and avoid this as it amounts to guessing.
The algorithm uses the last 1000 data points to not only identify sales, but also try and throw out false positives (when sales rank changes a small amount not due to sales but due to Amazon adjusting the ‘list’ of books being ranked in that category). This is typically a boon, but in some cases this can miss genuine sales.
If Amazon fails to update sales rank for that hour (common occurrence), that data is ‘lost’, because if a sale occurs during that time, by the time a new sales rank is presented, there is less differentiation.
Multiple sales on an individual order are represented as 1 sale by sales rank. See this post about Sales Rank Myths for more info.
Finally, sales rank is an ever changing secret formula which NovelRank’s algorithm is constantly trying to learn from. It will never be perfect, but I always hope it can keep up.

I hope this clarifies things for new authors. NovelRank exists so you can do more writing, selling, and living, so enjoy!

NovelRank 2012 Donation Drive

Mario Lurig - Creator

I believe that NovelRank authors will support the things they value, so I’ve decided that from now on there would only be one donation drive a year. Prove me right.

NovelRank is the creation of one individual, but benefits many authors worldwide. It costs over $1100/year in server costs just to keep things running. In the last year, NovelRank has kept pace with new worldwide domains to allow you to get a better idea of how your titles are doing in multiple Amazon sales regions. It has also added new CSV exports, added book cover image zoom, and fixed bugs reported by users. NovelRank is a solid source for you to maximize your marketing efforts and keep enjoying being an author. However, to keep this site free and keep improving it with new features, I need your support.

Here is the best part: By making any donation, even something as small as $5, puts you into a drawing to have your book featured on the website. Donate $25, $10, $5, or even make a total donation that equals $1 for each book you track. I’ll draw 15 email addresses from the supporters, and they will be contacted to identify the title they want to be featured on the website. It is my hope that this drawing will encourage more individuals to make donations and provide enough support to keep things rolling.

Finally, the Featured Books section on the TRACK page (highest traffic page on the website) are reserved for donations over $100. It’s a special thank you for those that are able to give more, so I’m offering them a little more.

Optional: Use the NovelRank Supporters Amazon Wishlist and send me an email.

Thank you in advance for supporting the site.

A note about recent donations: 7 titles have been ‘held over’ through the rest of 2012 due to high enough donation level (per previous donation drive rules) and being caught in-between the regular schedule. These are already in rotation as a thank you for their support.

New CSV Export – Full Date and Time Data

Hey look, a new feature! Added by request (thanks Tom from Greece), there is a new CSV export option available for you. When you are viewing a book’s detail page, you can use the button at the top to expand the Export to Excel/CSV options.

From there you will see a new link that will start the download of a single CSV file that contains the date, hour, and day of the week (screenshot is an early version) of every sale since tracking began. It’s sorted by newest dates first, but the date is in a standardized format which will allow you to sort the spreadsheet in the opposite direction using your spreadsheet program.

Previously, this data was only available through the charts and only for recent sales (for visibility), so this new feature provides a lot of functionality for quickly analyzing sales estimate data on your own. Finally, all CSV exports have been improved to support the newest domains on NovelRank: Italy, Spain, and China. Apparently, nobody noticed that these were not being exported. Don’t worry though, I noticed, and it is now fixed!

Free Kindle Books and Amazon Sales Rank Tracking

With the addition of the new Lending Library program which includes 5 days of free pricing for your kindle book, I thought it was time to write up a quick post to explain how sales rank on Amazon works in regards to free titles.

Amazon displays a separate sales ranking for books that are free compared to their paid sales rank categories (price of at least $0.01). While these are both visible on Amazon directly, the Amazon API that powers the sales rank tracking of every website, including NovelRank, will not report a sales rank for free books. This also means that if your book has a price one day, and then switches to free pricing for even just 1 day, it will no longer offer a sales rank that can be tracked until it becomes a paid title again. Here’s a breakdown of what will happen in terms of NovelRank.

Books switching to free will become inactive, and will not be able to be reactivated until they become paid again
Free books will not be available for tracking and will return a message stating that they cannot be tracked because they have no sales rank
Once a book becomes a paid book and thus is for sale, you can reactivate or track the book on NovelRank

The new Lending Library option to make your book free for 5 days during the 90 day period of exclusivity is phenomenal for promotional purposes, but please be aware that when that free period ends, you will need to reactivate the book for tracking on NovelRank.

I hope that clears up the free and paid sales rank issuess and how they will affect your ability to track sales rank info here on NovelRank.