NO.PZ202106160300004502
问题如下:
Based on Exhibit 1, Olabudo should calculate a prediction interval for the actual US CPI closest to:
选项:
A. 2.7506 to 2.7544
B. 2.7521 to 2.7529
C. 2.7981 to 2.8019
解释:
A is correct. The forecast interval for inflation is calculated in three steps:
Step 1. Make the prediction given the US CPI forecast of 2.8:
Step 2. Compute the variance of the prediction error:
Step 3. Compute the prediction interval:
2.7525±(2.0 x 0.0009)
Lower bound: 2.7525 - (2.0 x 0.0009) = 2.7506.
Upper bound: 2.7525 + (2.0 x 0.0009) = 2.7544.
So, given the US CPI forecast of 2.8, the 95% prediction interval is 2.7506 to 2.7544.
这个样本标准误0.0009在算confendence interval的时候不除以n开根吗? 另外,老师能否讲一下哪些描述需要除以n开根,哪些不需要除