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Table 2 The differences in properties of between GAS compared to other and classical measurement instruments

From: Goal attainment scaling as an outcome measure in rare disease trials: a conceptual proposal for validation

Classical measurement instrumentsGoal Attainment Scaling
Items and scoring options are fixedItems (goals) and scoring options (goal attainment levels) are different for each patient
Instrument can be used for many patients in many settingsPatients make their own personalized instrument for one occasion together with their clinician
Repeated measurements are possible, for example before and after an intervention, that can be comparedOnly one measurement is possible, after an intervention or after a defined period of time
The score is ‘anchored’, e.g. to a general population reference range, or to a cut-off score for a diagnosis, and is interpretable on individual levelThe score is not ‘anchored’ and can only be interpreted as a comparison of group means in a randomized setting
One or more unidimensional scales quantifying underlying constructsQuantifies change due to an intervention (or over time) that is relevant to patients