How will we know if the stimulus is working?

Something tells me David Axelrod was trying to dodge this question:

[CHRIS] WALLACE: Let’s turn to the stimulus plan. One of the president’s economic advisers, Austan Goolsbee, says there should be signs the package is working within six months and that one of the signs will be whether unemployment at the end of the year is 8 percent or 11 percent.

How quickly do you think we’ll know whether the package is working and how should we measure it?

AXELROD: Well, I think that there’ll be signs of activity very quickly. As you know, the package will help fund infrastructure programs and other programs that are ready to go around the country.

But it’s going to take time for that to show up in the statistics. The president has said it’s likely to get worse before it gets better. It is true that without this program, it could be — it could be much, much worse.

And so I don’t expect the arrow to bend down by the end of the year, but I do expect the rise in unemployment to be retarded by the things that were done this week.

WALLACE: So does six months sound like a fair marker to begin to see progress?

AXELROD: Well, I — it depends how you measure progress.

Regrettably, Axelrod didn’t say how progress should be measured.