Hi,
I have a silly problem that's driving me nuts. I have estimated two production function, with AR(1) correction. I got 7 point forecasts each and their standard errors (call each forecast series x1 and x2). I have computed the confidence intervals for each of these forecasts.
Then I have added the two forecasts into one series y=x1 + x2 and produced s.e. and confidence intervals for this series as well. What I need now is a confidence interval for the sum of y (ie total production from the two sites). How do I compute the standard error for this total? And does it actually make sense to do so?
Best
Meloria
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