Until now, the children’s bestseller lists have been divided into four categories: Picture Books, Chapter Books, Paperback Books and Series. Starting with the December 16 list (available online this Friday), however, the Chapter Books list will be divided into two lists for different age groups. More significantly, the children’s lists will include sales across all platforms, including ebooks (with the exception of the Picture Books list, which remains print-only). The paper outlined the changes in an announcement sent to publishers this week:

Starting in this issue, the children’s chapter book list has expanded into two categories: middle grade and young adult, both of which, along with the series list, now represent sales across all platforms — hardcover, paperback and e-books. Middle-grade books include those for children between the ages of 8 and 12, a category that encompasses many of the cherished books of childhood: “Charlotte’s Web,”  “A Wrinkle in Time,”  “Where the Red Fern Grows.” The young adult category includes all books published for readers 12 to 18, though as recent research shows, it’s very often adults between the ages of 25 and 34 snapping them up. Because these books have become so popular, we have also created extended lists of 15 titles each, which readers can access online.

The number-one title on the Young Adult list for the week of December 16 is The Perks of Being a Wallflower by Stephen Chbosky. First published by Simon & Schuster in 1999, it’s risen to popularity again with the launch of the movie this year. The number-one title on the Middle Grade list is the  Lego Ninjago Character Encyclopedia by Claire Sipi, published by DK.

In its announcement, the NYT concludes:

We believe these changes represent the best traditions in the way children read as well as the future of young people’s literature. Something for all ages, for the ages. That is — as all Y.A. dystopia readers know — until the next wave of technology comes along.

h/t Sarah Weinman

Iobyte’s Dan Lubart, who previously examined the effects of Kindle Sunshine Deals on the Kindle bestseller list, turns his attention to at the Nook and Kindle bestseller lists, alongside BN.com’s print bestseller list. “We found that there is a significant benefit to making these lists, and that benefit is far stronger for e-books than it is for print, where titles rise and fall in sales rank far more frequently,” he writes. “In fact, e-books that rise high on the bestseller list can normally look forward to a far longer time on the list than an equivalent print book.”

Lubart looks at “churn”–the number of titles that appear on the bestseller lists each day that weren’t on the list the previous day–on the Kindle, Nook, and BN.com (NYSE: BKS) print lists, and finds that there’s substantially less turnover on the e-book lists than on the BN.com print lists. “The ‘self-sustaining’ effect is far more prominent for e-books than it is for print,” he writes, “indicating that e-book purchases are more influenced by bestseller lists than print.”

Lubart also found that churn increases rapidly lower down the e-book lists (there’s much more turnover for titles 401-500 than for titles 1-100). An e-book hitting the Kindle or Nook bestseller lists is “highly beneficial,” he concludes, “not just for the status but for the actual sustained impact on additional sales it may provide.”

Lubart didn’t look at the New York Times bestseller lists–which, unlike the Barnes & Noble and Kindle lists, are updated only weekly and only list the 35 bestselling titles. It’s widely believed that the NYT list sells print books–a Stanford Business School professor looking at Nielsen BookScan sales found in 2005 that first-year sales of books that made the list increased, on average, by 13 or 14 percent–with a 57 percent increase in sales for debut authors.

But that research obviously took place before the NYT began including e-books on its bestseller lists. There is currently no BookScan-like resource tracking total sales of e-books, and, Lubart says, “I do track the NYT list for e-book fiction and non-fiction each week. Honestly, I have found next to no sales uplift for any titles that appear on that list so I left it out. It just doesn’t appear to drive additional sales (but it does make the authors happy). Also, it is smaller and more heavily curated so I would not be as trusting of the churn index since they aren’t clear about what gets filtered out.”

I asked Lubart why he thinks online retailers’ bestseller lists affect e-books sales more than print book sales. He attributes the effect to on-device browsing: “When I want to purchase a new book on a Kindle, unless I am setting out to buy a specific title, it’s very natural and almost inevitable that I will glance at the bestseller list. The devices make it very easy to do so, and the increased exposure is going to drive sales.” Meanwhile, when you buy a print book from Amazon (NSDQ: AMZN), “you are going through the website, where the bestseller list is not as prominent and the promotions are more personalized to your prior browsing and purchase history.”

Lubart says he is also open to other theories, and if you post them here, he’ll respond.