问题如下图：B1应该接受原假设等于零才对，为什么等于0.1279？
选项：
A. 
B. 
C. 
解释：
星星_品职助教 · 2019年12月13日
同学你好，
这道题的考点逻辑是：根据数据得出了系数（即题干中给出的b0，b1...等）并建立了一组回归方程。然后根据这组回归方程，给出一系列X的值进行预测Y。无论系数是否显著，只要方程建立出来了，就可以通过这个回归方程来得出一个Y的预测值。
而系数的检验则是证明预测结果是否正确的一种方法。如果检验后发现不能拒绝b1=0的原假设。就说明这个回归方程本身就是不成立的，也就不能使用。Y的预测结果自然也就是错误的。这个时候就需要修正后重新建立一组全新的回归方程来再度预测Y。而并不是将b1=0代入这个原有的错误的方程再预测。
举个直观的例子，如果所有系数b0，b1，b2....bn检验后发现都应该是0，这并不代表最后Y预测出来就是0，而是代表这个方程建立错误，需要重建方程再重新进行预测。
上课时讲的逻辑是先建立方程，然后检验系数，检验没问题后再预测。这道题的逻辑是先预测，然后通过检验系数来检验结果是否正确。这两种方法的本质都是预测Y和检验的过程，只是顺序不同。加油~
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？