Tag Archives: Sales

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!

Sales Rank Stats Return and Algorithm Updates

Sales Rank Stats

After many months of being restricted to the last 30-60 days, Sales Rank Stats have returned! Head over to a book’s details page (e.g. Example) and you can click the line titled Sales Rank Stats to show the book’s best, worst, average, and standard deviation in each domain that is being tracked. This information is updated the first time you access the page, and then will automatically update itself every 30 days. Unfortunately, real-time updating was making the page load very slowly, thus the 30 day cache was built. This should return page loading to It make take up to a minute to load the page for the first time!

I’ve turned up the power on the server to hopefully speed things up (it’s at max, which is ~$7/day) while everyone (including search engines) forces the statistics to be calculated. You may see some erratic slowness across the site while this occurs.

Sales Estimate Algorithm

After feedback and testing, I’ve improved the new algorithm to use tighter statistical analysis of sales rank changes. It is also now attempting to estimate for sales occurring when a book holds its rank (e.g. 700 last hour, 705 next hour) without improving. This is only for sales rank < 1000, but is also based upon the statistical median. Translation: It’s smart enough to deal with the differences between each Amazon domain as well as the Kindle or print distinction. Not only is it better than the last system I used, but it learns each day how to get better!

Final Note

These changes conclude the upgrades to NovelRank’s core that officially started on November 1st (but have been planned for months). As usual, I’ll keep an eye on things and make adjustments as necessary, but I think you can consider this NovelRank 2.0!

If you run into any problems like weird errors or broken pages, please let me know by sending an email to admin [at] novelrank {dot} com.

Major Update: Sales Estimates and Overall Speed

For the first week of November 2011, I went through the process of migrating 400,000,000 sales rank records into a new database system, in an effort to improve the performance of NovelRank, especially when you requested large amounts of data (e.g. charting). As of today, that migration was completed and NovelRank was updated (I didn’t eat today… it’s been a long day) to use this new system in 95% of requests. I didn’t think there would be as many problems as there were, thus why many of you reported strange changes hour-to-hour in your data. All of that should be resolved and the system mostly stable.

One big change is that as of Nov 1, sales estimates are being processed through a much more accurate (but not perfect) statistically based system for estimating the number of sales that occur per hour. The system still has a weakness for inaccuracy with a sales rank < 500 due to being based on sales rank changes, but it is a lot more accurate for Kindle Edition books, especially those not on Amazon.com. Due to some feedback today however, it seems that for some titles with sales rank < 500, it was still likely to be underestimating (and could be improved). I’ve made a tweak going forward that should increase sales estimates for those popular titles. I’ll continue to monitor the results throughout the month. This new system is constantly learning and reevaluating what constitutes a sale for a particular book/ebook, and it’s accuracy is increasing daily.

Please be aware that your sales estimates MAY HAVE CHANGED TODAY for the month of November as NovelRank was displaying the OLD sales estimates prior to today, while recording both the old and the NEW estimates (which are now being displayed).

There are still some issues with speed when calculating your BEST, WORST, and AVERAGE sales rank causing massive slowdown using the new system. For now, these calculations are still based on the old database structure, and I’ll be working this week to try and solve this problem. The end goal is to keep the speed and performance of NovelRank high and remove the downtime that occurs for a few hours every 2-3 months as well as for 30 minutes every evening at 1pm Pacific Time.

Finally, for those using the iPhone App, 40% of the data provided is from the old system (to keep the performance quick). Later this week you may see the stats change to ‘n/a’ for STD and AVG information as that data will be removed. I’ll be working with the App creator to see if an update is possible after the changes have been made.

Thanks again for using NovelRank, and I hope that it continues to be a useful tool in every authors arsenal.

Update: Nov 9, 2011

Some new fixes and adjustments have been put in place based on feedback. The system is now much tighter with the sales estimation algorithm, as well as it attempts to calculate sales for ‘holding rank’ when books have a sales rank that is better than 1000. As usual, estimates for popular titles will still be underestimated due to limitations of sales rank tracking.

Lesson Learned: Financial Motivations will Affect Book Sales

50 Conversation Starters Book Cover
Whether your intentions are good and your talents exceptional, if your motivations for writing are strictly financial, your book sales will suffer. Period.

It’s humbling, and it is hard, but it’s a lesson to be learned by established authors and new authors alike. A few months ago, I noticed that there was a price gap in the listed e-books for conversation starters or ‘book of questions’ style books. There were no books under $9.99, and thus nothing at the impulse $2.99 price point. So, since most who know me would agree that this was an area I was talented, I decided to design the type of book that would fit at that price point, write it, test the quality of the conversation starters using Amazon’s Mechanical Turk and a SurveyGizmo survey, and publish it across Amazon, Barnes & Noble, and the Apple bookstores.

Simple right?

  • Find price point
  • Write content
  • Publish
  • Profit!

The problem was my motivation for writing the book. Let’s be clear, I’m not giving up on it just yet (I have some great business cards that advertise the book in a unique way that I can leave around at social events), but the sales have been less than stellar. My goal was 200 sales per month, based upon some competition research and the price point. However, the best sales were the first few months, before 2 not-so-good reviews, and still sales were only at 30 copies per month. At that price point, I was still making more money and feeling better about each sale from my first book. Now, it’s not a direct comparison, because the books are not even in the same market or audience, but that’s not the point of the story.

Be careful of your motivations. Great books, regardless of audience; opportunity; or author, are written because they meet a need and were filled with the passion of the author. Sure, passion doesn’t sell books by itself either, but be careful that your goal isn’t, “To be the next Stephen King.” Rather, write about a topic that speaks to you and others, entertains, and you’ll be proud of when someone picks up a copy. Those are great authors, with smaller, sharper focus, driven by the content, not the dollar sign.