Editing Long tail (section)

===The longer tail over time===
A subsequent study by [[Erik Brynjolfsson]], [[Yu (Jeffrey) Hu]], and [[Michael D. Smith (economist)|Michael D. Smith]]<ref>Bynjolfsson, Erik; Yu (Jeffrey) Hu, and Michael D. Smith, 2010, [https://ssrn.com/abstract=1679991 "The Longer Tail: The Changing Shape of Amazon's Sales Distribution Curve"]</ref> found that the long tail has grown longer over time, with niche books accounting for a larger share of total sales. Their analyses suggested that by 2008, niche books accounted for 36.7% of Amazon's sales while the consumer surplus generated by niche books has increased at least fivefold from 2000 to 2008. In addition, their new methodology finds that, while the widely used power laws are a good first approximation for the rank-sales relationship, the slope may not be constant for all book ranks, with the slope becoming progressively steeper for more obscure books.

In support of their findings, Wenqi Zhou and Wenjing Duan not only find a longer tail but also a fatter tail by an in-depth analysis on consumer software downloading pattern in their paper "Online user reviews, product variety, and the long tail".<ref name="zd-2010">{{cite journal |url=https://ssrn.com/abstract=1742519 |last1=Zhou |first1=Wenqi |last2=Duan |first2=Wenjing |title=Online User Reviews, Product Variety, and the Long Tail: An Empirical Investigation on Online Software Downloads |date=21 November 2010 |journal=Electronic Commerce Research and Applications |volume=11 |issue=3 |pages=275–289 |doi=10.1016/j.elerap.2011.12.002 |s2cid=23070895 |url-access=subscription }}</ref> The demand for all products decreases, but the decrease for the hits is more pronounced, indicating the demand shifting from the hits to the niches over time. In addition, they also observe a superstar effect in the presence of the long tail. A small number of very popular products still dominates the demand.