Goal Attainment Scale

Abstract

The Goal Attainment Scale (GAS) is a highly individualized evaluation method designed primarily for monitoring progress toward specific, predetermined treatment objectives. It utilizes an ordinal 5-point scale, ranging from “much less than expected outcome” to “much more than expected outcome,” to quantify the extent to which a person achieves their unique goals. GAS functions as a structured method for translating broad, general aims into concrete, measurable working goals. This process enhances the organization of the intervention plan and ensures clinical focus is directed toward achievable outcomes. The resulting quantitative scores provide crucial insight into the degree of goal attainment, whether partial, complete, or absent.

Keywords

Goal Attainment Scale, GAS, individualized evaluation, ordinal scale, treatment goals, program evaluation, clinical outcome measurement, rehabilitation.

Authors

Kiresuk TJ, Sherman RE (1968); Dutch version adapted by the KNGF-richtlijn Ziekte van Parkinson (2016).

Purpose

The primary purpose of the Goal Attainment Scale (GAS) is to provide a systematic and objective framework for documenting and measuring progress toward highly specific, patient-centered goals within clinical and rehabilitation settings. Unlike standardized measures that assess fixed constructs, GAS allows clinicians and clients to collaboratively define success benchmarks tailored to the individual’s unique needs and circumstances.

This methodology is essential for effective program evaluation, enabling stakeholders to determine the effectiveness of interventions based on quantifiable shifts in patient behavior or status relative to their initial baseline. By requiring explicit, measurable definitions for five possible outcome levels, GAS transforms potentially vague clinical aspirations into clear, actionable metrics, thereby improving accountability and treatment focus.

Construct

The Goal Attainment Scale does not measure a fixed psychological construct or trait, but rather the relative attainment of an individualized evaluation objective. The core construct assessed is the degree of change or improvement achieved in specific behavioral or functional domains targeted by the intervention. This approach is rooted in the principles of idiographic measurement, where the individual serves as their own control.

The scale operationalizes success by defining five distinct levels of outcome severity or achievement, with Level 0 representing the expected outcome at the time of follow-up, and the extreme points (+2 and -2) representing outcomes significantly better or worse than anticipated. The construct, therefore, reflects the discrepancy between the predicted and observed outcome, quantifying the efficacy of the therapeutic process in achieving personalized treatment goals.

Validity

The validity of GAS is primarily established through its robust face validity and content validity. Because goals are collaboratively defined by the client and clinician, the resulting scale items are inherently relevant and specific to the individual’s concerns, ensuring high content validity for that particular case.

However, traditional psychometric validation (such as concurrent or predictive validity against standardized instruments) is complex for GAS due to the heterogeneity of the goals being measured across different individuals. Studies often focus on demonstrating criterion validity by correlating the overall GAS score (often calculated using a standardized T-score formula) with external measures of clinical change or functional improvement relevant to the specific population being studied.

Reliability

The reliability of the Goal Attainment Scale is predominantly assessed through inter-rater reliability, which measures the consistency of scoring when two independent raters evaluate the same outcome based on the pre-defined five-point scale. High inter-rater reliability is contingent upon the clarity and specificity of the goal definitions and the corresponding outcome levels. Vague or ambiguous goal definitions significantly compromise reliability.

Test-retest reliability is generally less applicable to GAS because the scale measures change over time, and the goals themselves are often dynamic and subject to modification as treatment progresses. Clinical protocols utilizing GAS emphasize comprehensive training for raters and precise operationalization of expected outcomes to maximize scoring consistency and minimize observer bias.

Factor Analysis

Traditional methods of factor analysis are typically not applied to the Goal Attainment Scale. Factor analysis is used to identify underlying latent constructs common across a set of fixed test items. Since GAS is an individualized instrument where each client has a unique set of goals (which may span diverse functional domains), aggregating these disparate goals for a common factor analysis is methodologically inappropriate.

Instead, psychometric evaluation focuses on the statistical properties of the aggregated T-scores derived from multiple goals across a population sample. These aggregate scores allow for group comparisons in program evaluation, but they do not reflect a common underlying factor structure in the way that fixed-item scales do.

Instrument

Test Type: Individualized Outcome Measure / Process Evaluation Tool

Format: Ordinal 5-point scale (standardized scoring procedure applied to individualized goals)

Language Available: Originally English (1968), widely translated and adapted, including a specific Dutch version (2016).

Population Group: Clinical, Rehabilitation, and Program Evaluation Settings

Age Group: Children, Adults, Elderly

Population Details: Used across various disciplines, including physical therapy (e.g., in the context of Parkinson’s Disease, as noted in the Dutch adaptation), mental health, and social work, focusing on monitoring functional change and participation.

Test Methodology: Collaborative goal setting between client and practitioner, defining five distinct levels of anticipated outcome (-2 to +2). Scoring is conducted at a predetermined follow-up period based on observable achievement relative to the defined levels.

Keywords

Idiographic measurement, rehabilitation outcomes, functional assessment, clinical scoring, Kiresuk, Sherman, goal setting, Activities, General Participation.

Authors

Author ORCID Identifier: N/A (Information not provided in source)

Affiliation Email addresses: N/A (Information not provided in source)

Correspondence Address: N/A (Information not provided in source)

Permissions & Fee and Test Year

The Goal Attainment Scale (GAS) was originally introduced in 1968 by Kiresuk and Sherman. As a methodological framework rather than a copyrighted proprietary instrument, the basic structure and methodology of GAS are generally free to use in clinical and research settings, although specific manuals or adaptations may carry usage fees or require permission. The Dutch adaptation for the KNGF-richtlijn Ziekte van Parkinson was published in 2016.

The original Explanation Form (Toelichtingsformulier) for the Dutch version can be downloaded here: Toelichtingsformulier PDF.

The original Measurement Instrument (Meetinstrument) for the Dutch version can be downloaded here: Meetinstrument PDF.

Reference’s

• Kiresuk TJ, Sherman RE. Goal attainment scaling: A general method for evaluating comprehensive community mental health programs. Community Mental Health Journal. 1968;4(6):443-453.

• KNGF-richtlijn Ziekte van Parkinson. (2016). KNGF Guideline for Physical Therapy in Parkinson’s Disease. Royal Dutch Society for Physical Therapy (KNGF). (Referring to the source of the Dutch adaptation).

• The Goal Attainment Scale is documented within the assessment toolkit for the KNGF guideline, emphasizing its use for measuring Activities and General Participation outcomes in rehabilitation contexts.

Items of the Goal Attainment Scale

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.

Goal Attainment Scaling does not consist of fixed items. Instead, it is a procedure used to create individualized scales. A typical GAS scale involves defining five levels of outcome for a specific goal (e.g., increased mobility, reduced anxiety):

• -2: Much less than expected outcome

• -1: Somewhat less than expected outcome

• 0: Expected outcome

• +1: Somewhat more than expected outcome

• +2: Much more than expected outcome