With all the buzz around Amazon's latest ebook reader Kindle, I tried to add it to Sales Rank tracking site Charteous, hoping to compare its popularity with other similar readers from Sony and Franklin over a period of time. Notice the emphasis on word tried, for although I could easily add Kindle to Charteous, it isn't possible to compare its Sales Rank with those of other eBook Readers. Why so? Just look at the Product Details section of Kindle:
As you can see, Amazon has created a whole new product category called Kindle Store for items related to its own eBook Reader. As the other eBook Readers are ranked within Electronics category, it is just not possible to compare their relative popularity through a eBook Readers Sales Rank Comparison Chart.
While digging for this blog post, I came across something else that didn't make sense: Kindle is not the only item within Kindle Store with a Sales Rank of 1 (highest possible rank). It shared this rank with digital book You: Staying Young: The Owner's Manual for Extending Your Warranty (You) (Kindle Edition) at the time I looked at almost the same time (Note: the ranking is updated every hour, so this may not hold when you try to confirm). Now, no one knows the secret algorithm that Amazon uses to calculate this rank and it may be possible the equal ranking is assigned by the algorithm, though that seems very unlikely to me.
A single instance of gaming the ranking system doesn't invalidate the whole notion of gauging popularity through Sales Rank, but it does confirm that even a company like Amazon is not immune from manipulating its system of recommendations and measurements to gain an unfair advantage.