With the limitation of our learning level and objective case, the variables x1, x2, . . ., xm being taken into account are only a part of all relevant variables . the other variables being ticked out may well be more important . so it is not plenty to think about the factor's influence on forecasting, the sample's information also play its role on forecasting 一般情況下,對因變量y有影響的因子往往為數(shù)極多,而由于我們的認識水平和客觀條件的限制,在問題中考慮進來的自變量x1,x2,...,xm只是全部有關(guān)變量的一部分,其它未被考慮進來的變量完全有可能是更重要的,可見,僅僅著眼于因子對預(yù)測的影響顯然不夠,樣品信息也對預(yù)測起著重要作用,而且每個樣品對預(yù)測所起的作用還互不相同。