k-period distributed lag model Y=A+B义+B义+B2X2+…+B义tA+ut(1413) Bo>B>B2 The effect of a unit change in the value of the explanatory variable is felt over k periods. B: the short-run /impact multiplier, which means “ the change in the mean value of Y following a un此t change in× in the same period” (B +B ).(B +B, +B,): interim/intermediate multipliers “… in the next, following period” ∑ B,=Bo+B,+B,+.+B, long-run/total multiplier. =nk-period distributed lag model Yt=A+B0Xt+B1Xt-1+B2Xt-2+…+BkXt-k+ut （14.13） B0＞B1＞B2 The effect of a unit change in the value of the explanatory variable is felt over k periods. ◼ B0 : the short-run /impact multiplier, which means “the change in the mean value of Y following a unit change in X in the same period” ◼ (B0+B1 ),(B0+B1+B2 ):interim/intermediate multipliers. “ ………in the next, following period” long-run/total multiplier. = = + + + + k i n Bi B0 B1 B2  Bk