As major hotel chains make a big push this year to increase the size of their loyalty programs through book-direct campaigns, they might take satisfaction in the fact that their programs grew at a healthy pace in 2015 but that presents a potential challenge — a large chunk of their rosters are inactive. Major chains saw their numbers of loyalty program members in 2015 increase an estimated 13.1 percent to more than 344 million members compared with 2014. [See note below on how we calculated those numbers]. But it’s likely that more than half of these memberships are inactive or lapsed, which generally means that a member hasn’t redeemed points or miles within the past year to 18 months. Get the full story at Skift