"We've had a huge run-up in the price of housing, and that doesn't show up in the C.P.I.," he said. So while the index shows that inflation is elevated but still under control — up 3.5 percent from April 2005 to April 2006 — many Americans find themselves paying sharply higher prices for essential goods and services.

In addition, aggregates generally are averages, which are of declining utility in an economy characterized by greater inequality of income and assets. In an interview with The Wall Street Journal in March, Mr. Snow took pains to point out that there had been substantial gains in per-capita income (8.2 percent, after inflation) and net worth (24 percent, before inflation) from the beginning of 2001 to the end of 2005.

The data he cited were averages, or means, and that can be misleading. "The average wage is a useful indicator if you want to know what's happening to the tax base, but it might not tell you what's going on for the individual worker," said Alan B. Krueger, an economics professor at Princeton and a former chief economist at the Labor Department. Consider a hypothetical country with 300 million workers. Say the chief executive of an investment bank gets a $300 million raise this year, while the other 299,999,999 workers don't get a raise. In the aggregate, the average per-capita salary has risen by $1, but only one person has more money in his pocket.

To see how typical workers are doing, it's better to look at median wages and incomes — the midpoint that separates the top 50 percent from the lower 50 percent. And median income, which was stagnant during President Bush's first term, is struggling to keep pace with inflation. "Median household income has gone nowhere since the turn of the decade," said Mark Zandi, chief economist at Moody's Economy.com.

Mr. Zandi puts the problem with averages another way. "If you put one foot in a tub of hot water and the other in a tub of cold water and take the average, everything is fine."

THIS dichotomy accurately describes the economy. From 2001 to 2004, the average net worth of an American family rose 6.3 percent, according to the Federal Reserve's Survey of Consumer Finances. But not everybody grew richer. For the bottom 40 percent of families by income, the median net worth fell. "It just doesn't resonate with people when the Treasury secretary says everything is fine," Mr. Zandi said. "It's fine for half the population, and it's clearly not for the other half."

There's a final reason that the aggregates may not accurately capture the public mood. Aggregates shed light on the performance of the economy in the last month, or in the last quarter. By contrast, measures of sentiments and polls gauge feelings about the present and expectations for the future.

"Consumers tend to view current conditions as quite favorable, but their expectations for six months down the road are rather pessimistic," said Ms. Franco of the Conference Board. "It could be that we're nearing a peak, and this is as good as it gets."