Mr. Brownstein and several academic experts trace much of widening class chasm to a shift by high-technology companies to hiring temporary workers.

Nationally, experts trace the harshening of attitudes toward juvenile offenders to the early 1990's, a time of soaring crime rates and sensational school shootings.

But many experts on health matters trace the decline to 1979, when local municipal officers were empowered to appoint hospital administrators.

Many experts trace the problems to a withering of scientific and technical expertise in the Government agency that runs the plants.

In fact, sometimes only an expert, a trained technician like myself, can see it and trace it.

Other experts have traced the relative decline of intellectuals to their concern race, ethnicity, and gender, and scholarly antiquarianism.

On the other hand, some experts trace the lower prices to the increase in the number of hogs on the market, which is partly attributable to contract farming.

Some experts trace its roots to an effort by a group of women in Japan in the 1960's to find pesticide-free foods.

Some experts trace its invention back to the second century B.C. and its widespread usage to the middle of the eighth century.

Some experts trace the problems to attitudes formed over more than 200 years as Navy men spent months at sea, isolated from society.