Like Ms. Casares, who works at a Victoria’s Secret store in Ocala, Fla., morebr and more employees across a growing range of industries find the number of hours they work is swinging giddily from week to week — bringing chaos not only to family scheduling, but also to family finances.br “Stable, predictable work schedules are essential to economic security,” said Susan J. Lambert, a professor at the University of Chicago who is studying new data supplied by the General Social Survey, a respected national surveybr that began asking in-depth questions about work schedules only last year.br “Since the 1970s, steady work that pays a predictablebr and living wage has become increasingly difficult to find,” said Jonathan Morduch, a director of the U. S. Financial Diaries project, an in-depth study of 235 low- and moderate-income households.br “The lowest hours I’ve gotten is 15 and the highest I’ve gotten is 39,” said Ms. Casares, who started in October, earning $10 an hour.br The latest data shows that 41 percent of all hourly workers say they are not given more thanbr a week’s notice of their schedule; nearly half have little or no say on their work hours.br “This shift has left many more families vulnerable to income volatility.”br Ever-changing schedules at Victoria’s Secret, for example, make it difficult for Ms.br Casares, 27, to find care for her 2-year-old and 6-year-old and to cover the bills.