老师，一元回归中t检验自由度不应该是n-k-1嘛？

问题如下：

1. The 95% confidence interval for b₀ is closest to:

Give the t-critical values as follow:

the t-critical values are all two-tails

选项：

A.

-0.0032 to +0.01375

B.

-0.0016 to +0.0025

C.

0.0008 to +0.01375.

D.

-0.0032 to +0.01378

解释：

A is correct.

考点：Confidence Interval in Linear Regression

解析：因为是48个月的数据，所以n=48，所以本题应该去查双尾95%的df=48-1=47的数据，即 the critical two-tailed 95% t-value = 2.012.

所以b0的95%的置信区间应该为 (0.0053-0.0042*2.012, 0.0053+0.0042*2.012) = (-0.0032, 0.01375)