One of the economic data points that usually snatches headlines is the monthly consumer confidence numbers that show how optimistic or pessimistic Americans are on the economy. But in a recent column, MarketWatch’s Mark Hulbert says to be careful about using those figures in your investing decisions.

Historically, Hulbert says, consumer confidence figures have been a lagging, not a leading, indicator for the stock market, and often serve as a contrarian indicator. “Perhaps the best factoid to illustrate how valuable the consumer confidence data is as a contrarian indicator: The highest level to which the Conference Board’s consumer confidence index has risen in the last 20 years came in January 2000, just weeks prior to the popping of the Internet bubble,” he says.

Hulbert also notes that the recent drop in consumer confidence occurred after the market had been heading downward, and that the last big drop in confidence (last June) came after the market had already entered a correction. And, he says, there’s more than anecdotal evidence. He writes, “A 2002 study by Kenneth Fisher of Fisher Investments and Meir Statman, a finance professor at Santa Clara University, found that ‘consumer confidence declines when stock prices decline but investors need not fear that declines in consumer confidence would be followed by low stocks returns… Low consumer confidence is followed by high stock returns more often than it is followed by low stock returns.'”