NO.PZ2020010801000019
问题如下：
The value of an F-test can be negative. True or false?
选项：
解释：
False. An F-test measures the reduction in the sum of squared residuals that occurs in the expanded model and depends on . This value is always positive because the unrestricted model must fit better than the restricted model.
如果n-k-1小于0呢？
