Hello all, Could anyone please help clarify the solution of april 2005 Q13(iii) on linear regression?In the question,the examiners state that we should determine the fitted regression of sickness rate on mortality which in my mind would be Ssm in the solution.In the examiner's report however,this was ignored while solving for beta and the rest of the solution,the examiners used Sms.Was the order of the regression just a red herring in this type of question?Thank you very much for your response.It will be very helpful to know where i have got this all wrong.
There's no difference between Ssm and Sms. If you look at the formula for Sxy on page 24 of the Tables then we see: Sxy = sum(xy) - n(xbar)(ybar) Swapping the x and y over makes no difference to the answer. PS As an aside normally we say regression of y on x yet we use Sxy - so they're being consistent with that - though frankly I think it's just an alphabetical thing...
thank you very much for your reply.Its one of the silly things that throw me off when solving past questions.this definitely helps to put me on the right track.tnx.
