"Maja" <[EMAIL PROTECTED]> wrote in news:[EMAIL PROTECTED]:
> Hi everyone, > > I was just doing some questions for practice b/c I have a midterm > coming up, and there is a question that I'm having lots of difficulty > with, it is not really covered in the textbook. > Here it goes: > Show that the least squares line y^=b1 + b2x passes through the point > (ybar,xbar), where ybar is the mean of y and xbar the mean of x. That should be (xbar,ybar) since convention is to write points with X first. The least squares line minimizes the sum of (y-b1-b2x)^2, which means that the first derivative of the sum (which is the same as the sum of the derivatives) will be zero. The first derivative of (y-b1-b2*x)^2 is 2*b2*(b1-y+b2*x); setting it to zero and summing results in ybar=b1+b2*xbar. . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
