The answer for the blank spaces is:
1) Can be Unreliable
2) The living standards include many factors and scenarios, it is quite possible that some or many of them do not qualify to be part of real GDP.
Real Gross Domestic Product (real GDP) is a macroeconomic measure of the estimation of financial output balanced for value changes.This alteration changes the cash value measure, nominal Gross domestic product, into an index for quantity of aggregate output.