Economists are "imperialists," says Elton Hinshaw. Without any qualms, they invade the turf of other professions, other fields of study and research.

"If there is a problem that is amenable to the tools we have, some economist will jump on it," says the retired secretary- treasurer of the American Economic Association (AEA).

Those tools include statistics, mathematics, "econometric modeling," equations, logic, and detailed analysis.

"Economics is what economists do," said the late Kenneth Boulding, who last taught at the University of Colorado.

But economists don't deal just with economic statistics, finance, monetary and fiscal policy, trade, investment, and other areas that one might associate with the title.

Today they are into everything, applying their tools to sociology, political science, criminology, education, healthcare - even happiness.

And their output is astounding.

The number of American economists may be slipping a little. Membership in the AEA several years ago was about 20,000. It's now close to 19,000. But the volume of their work has only grown, aided by increasingly powerful computers and the Internet.

The AEA's Journal of Economic Literature surveys some 300 economic journals. They range from the heavily mathematical, which appeal primarily to other economists, to the conversational, where a conscious effort has been made to eliminate the math for the benefit of a more general reader.

Many readers view such reports as a much-needed eye on Washington. The government's growing involvement in the 1950s and 1960s in many aspects of society - education, health, poverty reduction, housing, etc. - has prompted many economists to conduct empirical research on the impact and effectiveness of these programs.

"Economists have naturally followed," says Martin Feldstein, chief economist for President Ronald Reagan and now president of the National Bureau of Economic Research (NBER) in Cambridge, Mass.

Classical economic topics have been plowed by many brilliant economists for decades, and are still being probed today.

But increasingly, young economists explore new areas. They may find it more interesting, and perhaps not so subject to the academic attacks they might get from revisiting the work of respected peers.

That's apparent in the batch of NBER "working papers" this writer gets almost every day. They numbered 634 last year.

For a noneconomist, many are hard to decipher. But they usually have a readable summary. (See www. …