
The researchers found that although fiction books sold more copies than non-fiction books, non-fiction titles were more likely to retain their bestseller status once achieved. An example of this was Unbroken by Laura Hillenbrand, a non-fiction title that stayed on the bestseller list for 203 weeks, longer than any other book in the study, researchers said.
The fiction title that stayed on the list the longest was The Help, which stayed for 131 weeks; this may have been due to a popular film adaption, they said. The researchers also found that fiction writers had more repeat success with getting on the list than non-fiction writers.
Books in the romance category were more likely to be written by female authors and male authors were more likely to be authors of non-fiction books.
The researchers found no gender disparity among bestselling fiction authors, but most non-fiction bestsellers were written by men. They evaluated sales numbers and patterns from 2,468 fiction titles and 2,025 non-fiction titles from the New York Times Bestseller Lists 2008-2016 to create their formula for predicting how well a book would sell and whether it would be a bestseller.