The formula for calculating the U.S. poverty level needs updating, the leader of a national children's advocacy group said Monday.Nancy Cauthen, deputy director of Columbia University's National Center for Children in Poverty, said a family of four requires twice the federal poverty level of $21,200 to meet basic needs, The Biloxi, Miss., Sun Herald reported.The formula, devised in the 1960s, is based on a family spending one-third of its income on food. The 1968 poverty level for a family of four was $3,553, based on what the family would require for food costs multiplied by three, the report said. ...