ohai

Hi chaddy, well I don't understand why mean reverting equation have to be b0+b1=1 and we are assuming the best fitted line is exactly in 45 degree angle. The best fitted line may be more flatter or steeper, and as long as expected value of error term is 0, the line will produce unbiased forecasts (that's why I said sum of residuals being 0 is enough to mean the line is a best fitted one and the best fitted line should be unbiased, correct me if I am wrong). So can you help me what the first para of example 11 in page 305 means?