More recently, Nicholas Souleles (1999) uses income tax refunds to test the PIH. Since a refund depends on income in the previous year, it is predictable income and should thus not alter consumption in the year of its receipt. The evidence finds that consumption does indeed respond to the income refund, with a marginal propensity to consume between 35–60%. Melvin Stephens (2003) finds that the consumption patterns of social security recipients in the United States is not well explained by the PIH.