我不是高手,就第二个问题提供一点看法,供大家参考。我用的是Eviews6.0,在help里面的user guide的364-365页讲到这个问题。不是所有内容都能看懂,其中这几句我觉得最有参考价值:In practice, cases 1 and 5 are rarely used. You should use case 1 only if you know that all series have zero mean. Case 5 may provide a good fit in-sample but will produce implausible forecasts out-of-sample. As a rough guide, use case 2 if none of the series appear to have a trend. For trending series, use case 3 if you believe all trends are stochastic; if you believe some of the series are trend stationary, use case 4.