NO.PZ2019040801000038
问题如下：
Determine if this proposition is correct: In a simple linear regression, the appropriate number of degrees of freedom for the critical t-value used to calculate a confidence interval equals to the number of observations minus two.
选项：
A.correct.
B.incorrect, because the number of degrees of freedom for the critical t-value used to calculate a confidence interval is the number of observations.
C.incorrect, because the number of degrees of freedom for the critical t-value used to calculate a confidence interval is the number of observations minus one.
D.incorrect, because the number of degrees of freedom for the critical t-value used to calculate a confidence interval is uncertain.
解释：
A is correct.
考点：Hypothesis Test and Linear Regression
解析：在一元线性回归中，用于用t检验值构造置信区间的自由度数量，等于样本数减去2。因此命题正确。
老师你好，想问下在linear regression里面用到hypothesis test的有检验b0和b1是否为0，这里的df是等于n-1吗。然后用于检测CI的话，用的也是t test， 但是里面的df=n-k-1对吧。为什么呢，df跟用什么test没有关系跟检测什么有关吗。还有就是用t-test检测CI的话是指什么，就是检测b1是不是等于一个hypothesis value吗？谢谢
