TEXT OF COMMENTARY

Kai Ryssdal: Today's buying spree on Wall Street might make you wonder whether now is the time to dip your toe into those turbulent market waters. But how do you get your bearings in times like these? Commentator and economist Susan Lee has been drawn to the high seas.

SUSAN LEE: In a recession, the world is divided into two types. The worry-warts who obsessively check the value of their 401(k)'s and the optimists who start looking for the bottom. So, let's say you want to be the second type -- a forward-looking person. What do you do?

Well, a lot of people watch the leading indicators. These are 10 indices, put out by the Conference Board, which track variables like the S&P, consumer confidence and new building permits.

Fine. Except the leading indicators don't have a perfect track record. In the past, they've given off lots of false signals. For example, leading indicators often predict a recession when none happens. They falsely predicted five recessions since 1959. Even more problematic, the leading indicators track U.S. performance. Important? Yes, but not totally on the point for a global recession.

So I have something better. I suggest you watch an index that will tell you when the world economies are starting to perk up and when trade conditions are really starting to ease. It's called the Baltic Dry Index.

Essentially the Baltic Dry tracks the average daily price for shipping dry bulk like coal, iron ore, wheat and soybeans. There are three things that make it such a good leading indicator. One, the index looks at raw materials, so it captures activity at the very beginning of the production process. Two, it looks at ocean shipping, so it reveals what's happening to international trade -- the critical driver of global growth. And, three, the shipping business depends heavily on credit, so the Baltic Dry indicates whether credit is tight or loose.

Back in 2005, when the world's economies were just fine and credit was abundant, the Baltic Dry looked like a powerhouse. But it peaked in May of 2008. And it's been heading almost straight down ever since -- losing about 90 percent of its value.

So forget about your 401(k) and start paying attention to the Baltic Dry. And here's the really nice thing about starting now: You missed the six-month, worry-wart part when it tanked in such a nauseating fashion. In fact, one could almost say, the Baltic Dry has nowhere to go but up.

Kai Ryssdal: Susan Lee is an economist living in New York City.