Forecasting the future path of real GDP by exploiting past statistical relationships Question 1 options: 1) is never very reliable. 2) can be accomplished by the construction and use of an index of leading variables. 3) can be accomplished by the construction and use of an index of lagging variables. 4) can be accomplished by the construction and use of an index of coincident variables. 5) can only be accomplished if there is a perfectly positive correlation