strong expansionary effect of government spending, are peculiar to the unusual environment created by zero interest rates. He asserts that with positive interest rates a labor tax cut is expansionary, per the established literature, but at zero interest rates, it reverses and tax cuts become contractionary. Further, while capital tax cuts are inconsequential in his model with a positive interest rate, they become strongly negative at zero, and the multiplier of government spending is then almost five times larger. Paul Krugman wrote in December 2010 that significant, sustained government spending was necessary because indebted households were paying down debts and unable to carry the U.S. economy as they had previously: "The root of our current troubles lies in the debt American families ran up during the Bush-era housing bubble...highly indebted Americans not only can't spend the way they used to, they're having to pay down the debts they ran up in the bubble years. This would be fine if someone else were taking up the slack. But what's actually happening is that some people are spending much less while nobody is spending more—and this translates into a depressed economy and high unemployment. What the government should be doing in this situation is spending more while the private sector is spending less, supporting employment while those debts are paid down. And this government spending needs to be sustained..." John Maynard Keynes believed that government institutions could stimulate aggregate demand in a crisis: Stock market Some recessions have been anticipated by stock market declines. In Stocks for the Long Run, Siegel mentions that since 1948, ten recessions were preceded by a stock market decline, by a lead time of 0 to 13 months (average 5.7 months), while ten stock market declines of greater than 10% in the Dow Jones Industrial Average were not followed by a recession. The real estate market also usually weakens before a recession. However, real estate declines can last much longer than recessions. Since the business cycle is very hard to predict, Siegel argues that it is not possible to take advantage of economic cycles for timing investments. Even the National Bureau of Economic Research (NBER) takes a few months to determine if a peak or trough has occurred in the US. U.S. politics An administration generally gets credit or blame for the state of the economy during its time in office; this state of affairs has caused