On August 4, this question was posted. It was perfectly clear to anyone who knows really basic textbook stuff about linear regression but not to those who do not. I added some prefatory basic textbook material and voted to reopen, and then it was reopened.
Now I find this question closed because it is alleged to be unclear. With the one mentioned in the paragraph above, one can see that it was unclear to some because they don't know the basic textbook material, but with this one I cannot so readily surmise why it would be considered unclear.
I don't vote to close questions when I know that the reason why I don't understand them is that I don't know the subject area that the question is within. At this point I suspect that some other users do just that when the subject matter is elementary statistics.
Is there a policy that elementary statistics is in this regard to be treated differently from, for example, algebraic geometry or category theory?