Iain Duncan Smith explains poverty measure shift Plans to change the definition of child poverty from one linked to the average income to a broader set of criteria are to be outlined by the government. The Work and Pensions Secretary Iain Duncan Smith told the Today programme that "income matters" in the definition, but that it is better if the government also know if "life change" is taking place in families. "If you just give people on out-of-work benefits money you don't change their lives very much," he told John Humphrys. The key thing is, you attack poverty by knowing that what you do changes the lives of those people so that they move on and out of poverty.