Investors who slice and dice every economic and financial statistic under the sun are on shaky ground when it comes to one of the most important factors. Confidence, unlike measures of output or earnings, is intangible and consumers often fail to respond the way forecasters expect.

One would think, for example, that an economy in its fifth year of expansion and predicted to accelerate next year would have sentiment somewhere above average. But the closely watched Consumer Confidence Index, released by the Conference Board, fell to a seven-month low in November. Economists polled by The Wall Street Journal have higher hopes for Tuesday's release covering December, a rebound to 76.5. That still is fairly tepid given a base of 100 in 1985.

Economists puzzled by this may need to get out more. Indicators such as the unemployment rate show the strongest labor market in five years, but it is being flattered by an extremely low level of labor force participation. A housing recovery and record stock prices also are positives, but the rate of homeownership is at a 17-year low. And individual investors have only recently become net contributors to stock funds again.

At the moment, a narrow base of wealthy investors is benefiting disproportionately from rising stock and home prices. If recent trends continue, though, a broader swath of the population should begin to feel the positive effects.

With data going back to the late 1960s, including periods with even lower homeownership and individual-investor activity, the Consumer Confidence Index still shows peaks and troughs that coincided closely with those markets. Examples of the former are January 2000 and April 2006. Lows came in April 2009, October 2002, December 1974 and January 1980.