THE extensive coverage of the Astor family saga is just the latest example of America’s longstanding fascination with the very rich. But in recent years, the lifestyles of wealthy people have been not only a staple of popular culture but of serious economic research as well.

That’s because the wealthiest families have reaped enormous financial rewards over the last two decades, and their economic and political power has increased markedly. So it’s well worth asking what they are doing with all that money and what effect they are having on the overall economy.

Finding out where those income gains have gone, however, is about as easy as peering at the estates behind the towering hedges of Gin Lane in Southampton. There’s simply no official data on the economic behavior of the very rich. We can’t be sure how much they are saving or consuming, or exactly how they are using their accumulated wealth.

The wealthy are often thought to be big savers and, under President Bush, they have been given significant tax breaks. But what has actually become of their outsized gains in income?