Assessing the Reliability of the Future Years Defense Program and Building a Forecast

Abstract

Discerning, negotiating, and communicating priorities are necessary tasks for the U.S. defense acquisition system to effectively implement its portion of the National Defense Strategy. One of the Department of Defense’s central tools for doing so is the Future Years Defense Plan (FYDP), a projection of the cost and composition of the force over the next five years. However, the publicly released FYDP suffers from important limitations: there is tension between expressing administration preferences and accurate projection, no confidence intervals or other measures of reliability are provided, predictable budget elements have been transferred beyond the scope of the FYDP, and the detailed investment projections are challenging to gather and employ. This project works to make the FYDP more accessible and more easily evaluated. It posits two hypotheses using Fiscal Year (FY) 2018 budget request data: first, that FYDP projections could estimate actual 2019 spending more reliably than the President’s Budget alone, and second, that the reliability of projections would vary between services. The simple regression model employed found that the two-year-out FYDP projections significantly improved the reliability of estimates for procurement line items and RDT&E program elements.