Drifting O/T slightly to answer my own leading question...
A couple of things go against suggesting that a pay increase rise below the CPI is an effective pay cut.
In the late 90's, the CPI was restructured to represent a general index of price inflation, rather than a cost of living. The ABS express that "the CPI is often loosely called the "cost-of-living index", but strictly speaking this is not correct'.
Also, wage increases were previously linked to inflationary measures through the "Accord" (Hawke era), which took into account the CPI (ie. cost of living, at the time), in setting an increase in wages.
However from the late 90's this central wage-setting system has gradually moved to a decentralised enterprise level bargaining system, effectively decoupling the original link between wage increases and rises in the cost of living (of which the CPI, strictly speaking, was no longer a measure). Sure, CPI and 'cost of living' is often rolled out in enterprise bargaining, however that is applying a macro measure at a local level, when there are many local variations involving an enterprise that are not taken into consideration, conversely, when CPI is calculated at the macro level.
The ABS website goes on to say "The appropriateness of applying the CPI to individuals, or sub-groups of the population (eg, in adjusting their income or other money amounts involved in contractual arrangements), will depend among other things on the extent to which their particular expenditure pattern resembles the CPI weighting pattern. The significance of any divergence in the expenditure pattern of that particular individual or group from the average will, of course, depend on the relative dispersion of price movements. If the dispersion happens to be low (ie, all prices are changing at similar rates) the difference in expenditure patterns will be immaterial."
Comparatively, inflation was sustained at greater than 13% in the mid-70's, and wages increases did not match that level..
So, if a pay increase is less than inflation, is this an effective pay cut? One way to call it, but not effectively.
Is it a decrease in purchasing power? More likely.