 So they recommended that retailers manage their inventories for the entire holiday shopping season, with a leaner inventory at the start and new winter merchandise for the January sales.Michael P. Niemira, chief economist and director of research for the Shopping Center Council, states that he expects gift certificate usage to be between US$30billion and US$40billion in the 2006/2007 holiday shopping season.On the basis of the growing popularity of gift certificates, he states that "To get a true picture of holiday sales, one may consider measuring October, November, December and January sales combined as opposed to just November and December sales.