Girls' games and toys are a large yet difficult market for the children's toy industry. Creating games and toys that can be mass-marketed to girls is challenging for today's toy companies. Nancy Zwiers, an industry consultant and former head of worldwide marketing for Mattel's Barbie doll line, has pointed out the male-centred bias that makes development of girls' toys difficult: When I tour different company showrooms and look at what they're doing, many times it's a bunch of guys making decisions about what girls would like, and they miss the mark.