Thanks to author feedback from authors with access to Amazon DTP (Digital Text Platform) and thus real-time sales numbers for Kindle books, I was finally able to add more accurate sales estimates for Kindle Books. This includes tracking up to three sales per hour. For Kindle books selling as frequently as 7 books per day, the accuracy is up to 95% for sales estimates. For Kindle ebooks selling 30 or less per month, accuracy should be closer to 98%.
There is still room for improvement, but previously NovelRank’s accuracy was at 78% for books selling 3 or more per day or more specifically, multi-sale hours. Unfortunately, I don’t have the time to retroactively run sales history through the new formulas, so the accuracy is improved as of today moving forward. In all cases, including the future, NovelRank is underestimated book sales estimates on Kindle Edition books. I feel this is a better route that overestimating sales by 5%. Better safe than sorry.
Thanks again for the great feedback from authors to improve the accuracy of NovelRank book sales estimates on Amazon Kindle books.
Update: May 30, 2010 2:01am MDT
The new formula has been retroactively applied to all Kindle books tracked prior to 5/1/2010. You may notice slightly different sales numbers for your Kindle Edition books than you did previously.
Shawn: Formula tweaked, found it! Currently showing 27 sales for the best seller 9 instead of 11 for the timeframe you provided). Secondarily, there is no way to understand returns using SalesRank, so it’s a necessary evil.
Book 1) Tao – The Way – Special Edition ASIN:B002C75928
Shawn:
Can you provide the link or name of the best selling Kindle book so I can take a look? Or email me (you have the address).
It looks like the Kindle formula may not quite be completely fixed yet. Instead of tabulating too few books now, it seems to be tabulating too many.
On our top selling book so far this month, NovelRank shows us selling 11, where Amazon only shows us selling 8. That’s only 3 units difference, but then there have only been 3 days in the month so far.
Our second best selling title shows 5 units sold so far on NovelRank, and 5 units sold on Amazon, so that is correct.
The next best selling book shows 2 units sold on NovelRank, and 2 units have been sold on Amazon, but one was returned. This will probably not get subtracted in the NovelRank count at all, if past experience is any indication.
Not complaining in the least, just giving you more info to work with, as you continue to refine the process. ;0)
Shawn Conners
NovelRank checks every hour, from 2 minutes to 25 minutes past the hour as it goes through every book. There have been no lapses. The only possibility is Amazon’s API did not return a change, while the website did. Can’t adjust for that. If you had a specific example, email me (address in FAQ) and I can check logs.
Have the improvements affected how frequently NovelRank pulls data from Amazon for non-Kindle (i.e., paper) books? I’ve noticed over the past three or four days that Amazon sometimes goes through one or two hourly updates before NovelRank “catches up”. For example, NovelRank might show the 5:00 PM data point, and then not show a new one until 8:00 PM, despite updates visible on Amazon’s page at 6:00 PM and 7:00 PM.
Thanks for this great service!