Commentators on the US economy feel the US economy fell into a recession in 2001 and then proceeded into a slow-growth recovery due to a decline in investment. *Explain how a change in investment can have a big impact on GDP causing a nationwide slump. Recall that investment is small relative to the whole economy. *Illustrate your reasoning using our AD/AD model. *How did low interest rates combined with increased government spending on defense and homeland security alter the US economic outlook? Explain using our AD/AS model..