The projections in PREPARE are simply that — projections. A wide spectrum of forecasts can be found, even within the federal government itself. For example, the Congressional Budget Office projections will not always agree with those of the White House Budget Office.
In addition, no one knows what the future will bring. In August 2001, no one had factored into their economic projections the consequences of 9/11.
In early 2008, no one could have projected that our nation would have a deficit of $1.4 trillion in fiscal 2009.
In the same way, no one knows whether the economy will expand or contract over the next few years. No one knows what new legislation Congress might pass in the coming weeks and months. Thus, everyone must continually adjust their projections to account for changing circumstances.
Most of the projections you find in PREPARE are based on the current data available as of early 2014.