THREE WEEKS AGO in this column I wrote that my valuation model made stocks look attractive for the long term — but it was also saying that a short-term correction was due. My model sure was right about that correction. The model is based on just three factors: stock prices, corporate earnings and interest rates. Over the last three turbulent weeks prices are lower, earnings are higher, and interest rates are lower. All three factors have moved in the direction that makes stocks look like a better value. I don't have a firm conviction about whether stocks have literally hit...