4a317c29_lian_Broadcasting_Corporation___Definition
[Term] Parameter variations [Definition] 
Parameter variations refer to the budget’s assumptions about the economy (such as growth, inflation and unemployment) and how these will affect revenue and costs. The parameter variations in the MYEFO were vastly different to those set out in the PEFO, leading commentators to question whether they were massaged to provide a worst-case scenario, giving the Government more freedom to implement unpopular cuts and space for a miraculous recovery in the upcoming budget.
Budget 2014: Deficit tax may raise a lot less than Treasury forecasts says analyst - ABC News (Australian Broadcasting Corporation)
Definition