As soon as the New Year’s holiday ends and the American economy begins another calendar year, stock market observers can count on being assaulted by headline writers and business commentators using the phrase “As January goes, so goes the year.” The problem with that belief is that the data is often misused. To learn that the market stands a strong chance of being up at the end of the year after January has been up doesn’t mean much because, of course, the market already has a head start. It turns out that when you exclude January’s results, the predictive effect of the next eleven months weakens considerably, and there is a debate as to whether there is any predictive power to the first month of trading.