Policymakers look to the output gap as a measure of how the economy is performing. However, different methods of computing the output gap can lead to vastly different results, rendering it a potentially poor guide.
Ireland, Peter. "Changes in the Federal Reserve's Inflation Target: Causes and Consequences." Journal of Money, Credit, and Banking 39, no. 8 (December 2007): 1851-1882. (Working paper version of this article is also available.)