Disposable Personal Income The following is an excerpt from a May 1, 2006, press release issued by the Bureau of Economic Analysis. [monthly] disposable personal income (DPI) increased $78.4 billion...in March [2006] (Source: U. S. Burcau of SE. Economic Analysis) Use function notation to represent the disposable personal income at the end of March 2006 as a function of dispos- able personal income at the end of February 2006,