Hi All - would appreciate advice on the following:
I have an established Multiple Regression model (12 or so independent
variables). Is there a standard procedure for adding in new independent
variables at a later date (say 3 new variables)? Is there a criterion for
how much additional data to collect? Any advice here?
Designing a new Regression model (Single or Multiple - not sure yet) I'm
unsure as to nature of data I should collect (X data is panel `sizes' on
cars, trying to predict Y panel repair times from panel information). How
should I sample those X cases in population that do not occur often in
practice (smallest panel repairs, largest panel repairs), and which will
not be predicted often - BUT will nevertheless feature from time to time.
Thing is the population of variables are mostly `middle-scale' repairs, and
this is where regression model will be required most often. Should I sample
over all `sizes' irrespective of how often they feature in practice, or
instead just concentrate on those x-values that appear most often?
Any particular books/sources useful for these sorts of issues?
many thanks in advance.
Murray Doyle
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