The Whitehouse pats itself on the back in this report. Obama says that he knows that the stimulus worked because his staff of economists set up a controlled experiment in an alternative universe where no stimulus was applied.
“Following implementation of the act, the trajectory of the economy changed materially toward moderating output decline and job loss,” the president’s Council of Economic Advisers told Congress.
It looks like somebody needs a lesson in post hoc ergo propter hoc. I’m sure their statistics are all nice and tidy, though.