问题如下图：
选项：
A. 
B. 
C. 
，为何是t-4减t-5,而不是t-3减t-4呢？
解释：
NO.PZ201709270100000506 问题如下 6. Baseon the regression output in Exhibit 3 ansales ta in Exhibit 4, the forecastevalue of quarterly sales for Mar2016 for PowereP is closest to: A.$4.193 billion. B.$4.205 billion. C.$4.231 billion. C is correct. The quarterly sales for Mar2016 is calculatefollows:beginarraylln Salest-ln Salest-1=b0+b1(ln Salest-1-ln Salest-2)+b2(ln Salest−4-ln Salest-5)ln Salest−ln3.868=0.0092−0.1279(ln3.868−ln3.780)+0.7239(ln3.836−ln3.418)ln Salest=1.44251Salest=e1.44251=4.231begin{array}{l}\ln{\text{ Sales}}_\text{t}{\text{-ln Sales}}_\text{t-1}{\text{=b}}_\text{0}{\text{+b}}_\text{1}{\text{(ln Sales}}_\text{t-1}{\text{-ln Sales}}_\text{t-2}{\text{)+b}}_\text{2}\text{(ln Sales}_{t-4}^{}{\text{-ln Sales}}_\text{t-5}\text{)}\\\ln{\text{ Sales}}_\text{t}-\ln3.868=0.0092-0.1279(\ln3.868-\ln3.780)+0.7239(\ln3.836-\ln3.418)\\\ln{\text{ Sales}}_\text{t}=1.44251\\{\text{Sales}}_\text{t}=e^{1.44251}=4.231beginarraylln Salest-ln Salest-1=b0+b1(ln Salest-1-ln Salest-2)+b2(ln Salest−4-ln Salest-5)ln Salest−ln3.868=0.0092−0.1279(ln3.868−ln3.780)+0.7239(ln3.836−ln3.418)ln Salest=1.44251Salest=e1.44251=4.231 0.0092−0.1279(ln3.868−ln3.780)+0.7239(ln3.836−ln3.418)得出来不是0.089776吗 然后怎么算ln（Sales t）呢？
NO.PZ201709270100000506问题如下6. Baseon the regression output in Exhibit 3 ansales ta in Exhibit 4, the forecastevalue of quarterly sales for Mar2016 for PowereP is closest to: A.$4.193 billion.B.$4.205 billion.C.$4.231 billion.C is correct. The quarterly sales for Mar2016 is calculatefollows:beginarraylln Salest-ln Salest-1=b0+b1(ln Salest-1-ln Salest-2)+b2(ln Salest−4-ln Salest-5)ln Salest−ln3.868=0.0092−0.1279(ln3.868−ln3.780)+0.7239(ln3.836−ln3.418)ln Salest=1.44251Salest=e1.44251=4.231begin{array}{l}\ln{\text{ Sales}}_\text{t}{\text{-ln Sales}}_\text{t-1}{\text{=b}}_\text{0}{\text{+b}}_\text{1}{\text{(ln Sales}}_\text{t-1}{\text{-ln Sales}}_\text{t-2}{\text{)+b}}_\text{2}\text{(ln Sales}_{t-4}^{}{\text{-ln Sales}}_\text{t-5}\text{)}\\\ln{\text{ Sales}}_\text{t}-\ln3.868=0.0092-0.1279(\ln3.868-\ln3.780)+0.7239(\ln3.836-\ln3.418)\\\ln{\text{ Sales}}_\text{t}=1.44251\\{\text{Sales}}_\text{t}=e^{1.44251}=4.231beginarraylln Salest-ln Salest-1=b0+b1(ln Salest-1-ln Salest-2)+b2(ln Salest−4-ln Salest-5)ln Salest−ln3.868=0.0092−0.1279(ln3.868−ln3.780)+0.7239(ln3.836−ln3.418)ln Salest=1.44251Salest=e1.44251=4.231 为什么t-statics不合格的系数也会被放进公式，b0和b1的t检验就过不了啊
NO.PZ201709270100000506 问题如下 6. Baseon the regression output in Exhibit 3 ansales ta in Exhibit 4, the forecastevalue of quarterly sales for Mar2016 for PowereP is closest to: A.$4.193 billion. B.$4.205 billion. C.$4.231 billion. C is correct. The quarterly sales for Mar2016 is calculatefollows:beginarraylln Salest-ln Salest-1=b0+b1(ln Salest-1-ln Salest-2)+b2(ln Salest−4-ln Salest-5)ln Salest−ln3.868=0.0092−0.1279(ln3.868−ln3.780)+0.7239(ln3.836−ln3.418)ln Salest=1.44251Salest=e1.44251=4.231begin{array}{l}\ln{\text{ Sales}}_\text{t}{\text{-ln Sales}}_\text{t-1}{\text{=b}}_\text{0}{\text{+b}}_\text{1}{\text{(ln Sales}}_\text{t-1}{\text{-ln Sales}}_\text{t-2}{\text{)+b}}_\text{2}\text{(ln Sales}_{t-4}^{}{\text{-ln Sales}}_\text{t-5}\text{)}\\\ln{\text{ Sales}}_\text{t}-\ln3.868=0.0092-0.1279(\ln3.868-\ln3.780)+0.7239(\ln3.836-\ln3.418)\\\ln{\text{ Sales}}_\text{t}=1.44251\\{\text{Sales}}_\text{t}=e^{1.44251}=4.231beginarraylln Salest-ln Salest-1=b0+b1(ln Salest-1-ln Salest-2)+b2(ln Salest−4-ln Salest-5)ln Salest−ln3.868=0.0092−0.1279(ln3.868−ln3.780)+0.7239(ln3.836−ln3.418)ln Salest=1.44251Salest=e1.44251=4.231 ln Salest-1-ln Salest-2的t检验是-1.1252，小于criticvalue2.03，所以接受原假设，即系数等于零。
NO.PZ201709270100000506 问题如下 6. Baseon the regression output in Exhibit 3 ansales ta in Exhibit 4, the forecastevalue of quarterly sales for Mar2016 for PowereP is closest to: A.$4.193 billion. B.$4.205 billion. C.$4.231 billion. C is correct. The quarterly sales for Mar2016 is calculatefollows:beginarraylln Salest-ln Salest-1=b0+b1(ln Salest-1-ln Salest-2)+b2(ln Salest−4-ln Salest-5)ln Salest−ln3.868=0.0092−0.1279(ln3.868−ln3.780)+0.7239(ln3.836−ln3.418)ln Salest=1.44251Salest=e1.44251=4.231begin{array}{l}\ln{\text{ Sales}}_\text{t}{\text{-ln Sales}}_\text{t-1}{\text{=b}}_\text{0}{\text{+b}}_\text{1}{\text{(ln Sales}}_\text{t-1}{\text{-ln Sales}}_\text{t-2}{\text{)+b}}_\text{2}\text{(ln Sales}_{t-4}^{}{\text{-ln Sales}}_\text{t-5}\text{)}\\\ln{\text{ Sales}}_\text{t}-\ln3.868=0.0092-0.1279(\ln3.868-\ln3.780)+0.7239(\ln3.836-\ln3.418)\\\ln{\text{ Sales}}_\text{t}=1.44251\\{\text{Sales}}_\text{t}=e^{1.44251}=4.231beginarraylln Salest-ln Salest-1=b0+b1(ln Salest-1-ln Salest-2)+b2(ln Salest−4-ln Salest-5)ln Salest−ln3.868=0.0092−0.1279(ln3.868−ln3.780)+0.7239(ln3.836−ln3.418)ln Salest=1.44251Salest=e1.44251=4.231 ln3.868−ln3.780 用计算器怎么按 算式列对了，一直得不到正确答案 ， 是不是和计算器设置有关？
NO.PZ201709270100000506 问题如下 6. Baseon the regression output in Exhibit 3 ansales ta in Exhibit 4, the forecastevalue of quarterly sales for Mar2016 for PowereP is closest to: A.$4.193 billion. B.$4.205 billion. C.$4.231 billion. C is correct. The quarterly sales for Mar2016 is calculatefollows:beginarraylln Salest-ln Salest-1=b0+b1(ln Salest-1-ln Salest-2)+b2(ln Salest−4-ln Salest-5)ln Salest−ln3.868=0.0092−0.1279(ln3.868−ln3.780)+0.7239(ln3.836−ln3.418)ln Salest=1.44251Salest=e1.44251=4.231begin{array}{l}\ln{\text{ Sales}}_\text{t}{\text{-ln Sales}}_\text{t-1}{\text{=b}}_\text{0}{\text{+b}}_\text{1}{\text{(ln Sales}}_\text{t-1}{\text{-ln Sales}}_\text{t-2}{\text{)+b}}_\text{2}\text{(ln Sales}_{t-4}^{}{\text{-ln Sales}}_\text{t-5}\text{)}\\\ln{\text{ Sales}}_\text{t}-\ln3.868=0.0092-0.1279(\ln3.868-\ln3.780)+0.7239(\ln3.836-\ln3.418)\\\ln{\text{ Sales}}_\text{t}=1.44251\\{\text{Sales}}_\text{t}=e^{1.44251}=4.231beginarraylln Salest-ln Salest-1=b0+b1(ln Salest-1-ln Salest-2)+b2(ln Salest−4-ln Salest-5)ln Salest−ln3.868=0.0092−0.1279(ln3.868−ln3.780)+0.7239(ln3.836−ln3.418)ln Salest=1.44251Salest=e1.44251=4.231 在经典题36页明确标明了 用这个mol : “ ln Salest-ln Salest-1=b0+b1(ln Salest-1-ln Salest-2)+b2(ln Salest−4-ln Salest-5)”但是课后题这边是“ ln Salest-ln Salest-1=b0+b1(ln Salest-1-ln Salest-2)” ，所以我的问题是，哪一边的出错了？ 考试时，会按照哪种来？
