But to estimate the answers to such questions, economists rely on models based on historical relationships between various policies and real-world results. Earlier this month, Zandi and co-author Alan Blinder, former vice chairman of the Federal Reserve, released the most detailed assessment of the government's efforts to combat the so-called Great Recession. Neither economist is regarded as a partisan firebrand. Zandi, for example, backed John McCain in the 2008 presidential campaign and has advised members of both parties.
Their conclusion: The fiscal stimulus created 2.7 million jobs and added $460 billion to gross domestic product. Unemployment would be 11% today if the stimulus hadn't been passed and 16.5% if neither the fiscal stimulus nor the banks' rescue had been enacted, according to Zandi and Blinder. "It's pretty hard to deny that it had a measurable impact," Zandi said.