From an article by Leigh Zaleski Sociologists and advocates for the poor use alternative formulas to determine the minimum level of income required for a family to sustain itself. The Self-Sufficiency Standard, for example, considers regional variation in living expenses and accounts for food, housing, child care, health care, transportation, taxes and other costs. Last year, the Standard estimated the cost of living in York County for a single parent with a preschooler and school-age child was $42,114, which requires an hourly wage near $21.60. In comparison, the federal poverty line for a family of three is $18,530, which comes out to $9.50 an hour earned by a single parent working 40 hours a week. One in five households in Pennsylvania lacked self-sufficiency wages last year, according to an analysis by the Center for Women's Welfare at the University of Washington. In 85 percent of these households, at least one adult was working.