Walmart's warehouse club assembled a growing army of fans to help in its race against Costco

The Member's Mark Community helped Sam's Club design these jogger pants. Dominick Reuter/Business Insider Walmart's warehouse club is taking customer feedback to another level. Sam's Club said it has a 150,000-member engagement community that helps it develop new products. The chain's chief merchant said the program helps his team get what shoppers want. Focus groups are a mainstay of retail, but Walmart's warehouse club is taking it to another level in its battle against Costco. Sam's Club...