What goal attainment scaling is
Goal attainment scaling was introduced by Kiresuk and Sherman in 1968 to evaluate mental health services. It is now widely used in allied health, rehabilitation, early childhood intervention and disability services.
Standardised tests compare a person with others. GAS does something different: it measures change against goals that are personal to the participant. That makes it useful when the goals are about real life, such as catching a bus alone, joining a sport or dressing without help, rather than a test score.
How the scale works
For each goal, the participant, family and practitioner write five possible outcome levels before the support starts. Each level must be specific and observable, so anyone reading it can tell which one was reached.
- Plus 2: much more than expected
- Plus 1: somewhat more than expected
- 0: the expected outcome by the review date
- Minus 1: somewhat less than expected
- Minus 2: much less than expected
Where the starting point sits
Many practitioners set the current level of performance at minus 1 or minus 2, depending on whether things could get worse. For example, if a person currently needs help to plan a trip and could lose skills without support, the starting point might be minus 1, leaving minus 2 for a decline.
Goals can be weighted for importance or difficulty, and the scores across several goals can be combined into a single summary score, often called a GAS T score. Many services simply report the level reached on each goal, which is easier for families and planners to read.
A simple example
Goal: catch the bus to TAFE on my own within 6 months.
- Minus 2: still needs a worker on the bus for the whole trip
- Minus 1 (now): needs a worker for the whole trip but chooses the route
- 0: travels alone, with a worker meeting at TAFE, 3 days a week
- Plus 1: travels alone both ways, 3 days a week
- Plus 2: travels alone both ways and to one other place each week
Why it matters for the NDIS
NDIS plans are built around the participant's goals, and funding at reassessment depends on evidence about what supports are working. A progress report that shows GAS levels for each goal tells the NDIA, in a clear and comparable way, what changed and what still needs support.
With community participation and daily living skills budgets reduced by the October 2026 funding reset, clear outcome evidence helps participants make the case for supports that are making a difference, and helps everyone decide which supports to change.
Tips for using GAS well
- Write goals with the participant in their own words, then build the scale together
- Make each level observable: what, how often, with how much help, by when
- Keep the gaps between levels roughly even
- Set a review date that matches the plan or service agreement period
- Use GAS alongside standardised measures, not instead of them, when the NDIA needs functional evidence