The ECPA Bestseller Lists are compiled using adult book sales data from Christian retail stores across the U.S. A book must have sales in at least 20% of reporting stores during at least one week of the represented reporting cycle to be placed on the list. Only Trade Paper, Cloth and Mass Market Paper books are reported, tracts, mini-books or booklets are not included on this list. Only books which are offered to Christian stores at a trade discount from a publisher or wholesaler are featured on the list. Seasonal/holiday books are omitted from this list.