The Gilliam Autism Rating Scale – 3rd Edition

Paper Info
Page count 5
Word count 1512
Read time 6 min
Topic Psychology
Type Essay
Language 🇺🇸 US


The selected test is GARS-3 (Gilliam Autism Rating Scale – 3rd edition) which is used to identify and diagnose Autism Spectrum Disorder (ASD). Intended for individuals aged 3-22, the test consists of fifty-six items that are assessed on a 4-point ordinal scale, taken with a paper and pencil, that can be administered by most anyone. The subscale elements measure aspects of communication, maladaptive speech, emotional response, social interaction, repetitive behaviors and restrictive behaviors (Gillian, 2004).

Furthermore, the GARS collaborates closely with the DSM domain to provide external feedback and progressive instructional reasoning in the event a differential diagnosis is needed, with the capability to distinguish severity of ASD. This report will evaluate GARS-3 under the elements of The Code of Fair Testing Practice in Education and provide recommendations to its applicability in a school setting.

The Code of Fair Testing Practice in Education

Element 1: Purpose

The GARS-3 is a norm-referenced assessment test used to identify ASD and its severity in an individual, designed for ages 3-22. One of the benefits of its purpose is the availability of the test to non-healthcare professionals such as educators or counselors to conduct initial assessment of ASD. However, the negative aspect of its purpose is that the identification process is not fully reliable and leads to missed diagnoses. GARS-3 has sections which seek to quantify data with subscales based on emotional, verbal, social, and cognitive behaviors that encompass most elements of ASD-associated identifiable characteristics in school-aged individuals (Gilliam, 2014).

Element 2: Appropriateness

ASD is a developmental disorder which causes issues for an individual with social and emotional reciprocity, speech patterns, repetitive patterns, and attention deficit among other behaviors (Cooper et al., 2007). GARS-3 seeks to analyze these aspects through six different sub-scales designed into the test which measure emotional responses, social communication, social interaction, maladaptive speech, and repetitive and restrictive behaviors (Gilliam, 2014). A strength of this test is that it aligns with necessary DSM-5 criteria, making it a valid assessment of a mental disorder. However, considering that autism is a complex condition that can manifest in a variety of ways, a paper and pen assessment test may not be clinically accurate in its identification.

Element 3: Materials

The materials for the test are simple including an examiner’s manual, 50 summary/response forms, and an instructional objective manual. It can be done via paper and pencil or online (Gilliam, 2014). The benefit of this test is accessibility on that it requires minimum material and offers clear instructions. However, a weakness is that an online version offers more psychometric properties and can be more accurate than the paper version.

Element 4: Training

In theory, anyone can administer the GARS-3 with minor preparation, with the raters usually selected as parents, caregivers, or teachers of the tested individual (Boni, 2017). They must have been in contact with the person for at least 2 weeks (Karren, 2017). Meanwhile, examiners are recommended to be highly trained professionals with autism experience. A weakness of the test is that bias is a possibility on behalf of the raters and stress from parents worried about a child’s condition (Devries, 2017). At the same time, a strength of minimal training required allows this assessment to be performed in a wide variety of locations, including where a trained professional may not be readily available.

Element 5: Technical Quality

Technical quality of GARS-3 has been controversial at times, but generally its approach with sub-scale elements and rating system has been praised as a reliable indicator of identifying ASD in non-clinical settings. Although only a moderate amount of research has been conducted with GARS-3, it is believed to be a significant improvement over the validity of its predecessor GARS-2 (Boni, 2017).

However, the quality remains high for the conditions, as in one study a mother was able to rate task analysis carried by her son with the results indicating inter-rater reliability corresponded with information for GARS-3 (O’Handley, 2017). Meanwhile, parents also rate behavioral characteristics well, with indicating that children have a high probability of ASD (Devries, 2017). These examples demonstrate that technical components of GARS-3 can be reliable in consistency of identifying ASD on DSM-V scales.

Element 6: Test Items and Format

Information is filled out by raters on a questionnaire of 56 items using the Likert rating system, with scales ranging 0-3. All sections need to be completed regardless if they pertain to the subjects. Scores are totaled by the examiners which produce subscale index scores which are compared to the normative in the manual (Karren, 2017). A weakness is that different individuals administer and score the test, which may result in discrepancies. A strength of the test format is that its quantifiable and easy to follow for non-clinical professionals.

Element 7: Test Procedures and Materials

Materials offered for the test offer all necessary components to conduct and score the test by raters and examiners. All instructions are included and guidance on how to interpret results are given. GARS-3 is meant to be a standardized accessible assessment administered by individuals who are not health professionals, thus fair and appropriate to broader populations. The test also offers material on how to proceed next depending on results, including guidance on strategies for treatment and management of ASD in young individuals (Karren, 2017). There are no identifiable weaknesses regarding materials and procedure.

Element 8: Modifications and Accommodations

GARS-3 is available in English and Spanish as well as accommodations for individuals with speech impairments. If the test-taker cannot fulfill the language requirement, the GARS-3 can be modified to evaluate only 4 of the 6 scales (Karren, 2017). The strength is that the test format is designed to be accommodating as possible as well as developing with technological advances with digital input, improving easy and efficiency.

Element 9: Group Differences

Since GARS-3 is not a performance-based assessment, diversity aspects do not apply. Scores between subgroups can be compared by analyzing normative date used to compile index scores as well as demographic information. The Caucasian population accounts for 78% of the normative sample and almost evenly split 51-49% between males and females, which matches the epidemiology of the condition (Gilliam, 2014). Making GARS-3 a non-performance measuring assessment is beneficial in the context of the lack of diversity. However, a weakness of the test is that a rater can be bound to human error and biases towards an individual, scoring behaviors based on perceptions, previous relationship, or personal stress level – all of which may affect the scores (Boni, 2017).


Overall, GARS-3 is a strong, comprehensive initial assessment for ASD that can be conducted in non-clinical settings by non-healthcare professionals. It is designed in its procedures, materials, and scoring elements to be widely available to anyone, offering the potential for initial identification of suspected ASD diagnosis based on DSM-5 parameters. The test uses a 2-step system of a rater familiar with the child scoring the behaviors based on a 56-item questionnaire with a Likert scale, and an examiner totaling and evaluating the scores based on professional experience and manual guidelines. The test kit provides all necessary materials, does not take a prolonged amount of time, and offers detailed instructions and guidelines.

Overall recommendations

GARS-3 is the newest edition of the test and has undergone significant changes in comparison to the previous version, updated to reflect DSM-5 criteria. Although GARS-3 can potentially be recommended as an initial tool for identifying elements of ASD in students, it is not recommended to use the results of this test alone as in practical applications it has shown certain weaknesses. There are validity concerns regarding the ability of the test to differentiate between ASD and intellectual disability, with scores showing weak relationships to more specific ADOS-2 and CARS-2 test scores (U.S. Department of Education, n.d.).

There have been concerns as well that inconsistencies exist surrounding the response values based on the guidelines in the manual and the response form, creating potential for misinterpretation. Poor sensitivity and underidentification of ASD along with questionable test structure is concerning. However, no test is perfect and experts highlight the need to use multiple assessment tools in a comprehensive development diagnosis (Wilkinson, 2016).

Recommendations for improvement of GARS-3 would focus on bettering internal consistency that would improve both the sensitivity and specificity of the test for identifying ASD. The ID individuals provide a small norm sample with higher scores. In comparison to clinical scores, non-ASD subsamples score on the lower-end as “possibly present” range which is inaccurate. Another potential issue for improvement are the scales which demonstrate a lack of near perfect convergence between factor-based scales and the GARS subscales. It can result in discrepant items assigned to wrong subscales.

While the test is made to be administered by anyone, its intention to identify individuals suspected of having ASD is challenging. Studies indicate that professionals with experience working with mental health and ASD are able to more commonly and accurately identify ASD using GARS (Volker et al., 2016). This is an issue for a test which positions itself as a broad spectrum assessment that anyone can reliably administer to test for ASD.


Boni, T. M. (2017). Parental stress and autism spectrum disorders: Differential effects of social subtypes and parent gender. Web.

Cooper, J. O., Heron, T. E., & Heward, W. L. (2007). Applied behavior analysis. Hoboken, NJ: Pearson.

Devries, L. (2017). The role of child characteristics, parental self-efficacy, and social support on parental stress in mothers and fathers of children with autism spectrum disorders. Web.

Gilliam, J. E. (2014). Gilliam Autism Rating Scale–Third Edition. Austin, TX: PRO-ED.

Karren, B. C. (2016). A test review: Gilliam, J. E. (2014). Gilliam Autism Rating Scale–Third Edition (GARS-3). Journal of Psychoeducational Assessment, 35(3), 342–346. Web.

O’Handley, R. D., & Allen, K. D. (2017). An evaluation of the production effects of video self-modeling. Research in Developmental Disabilities, 71, 35–41. Web.

U.S. Department of Education. (n.d.). Best practices for school based assessment of ASD. Web.

Volker, M. A., Dua, E. H., Lopata, C., Thomeer, M. L., Toomey, J. A., Smerbeck, A. M., … Lee, G. K. (2016). Factor structure, internal consistency, and screening sensitivity of the GARS-2 in a developmental disabilities sample. Autism Research and Treatment, 1–12. Web.

Wilkinson, L. A. (2016). A best practice guide to assessment and intervention for autism spectrum disorder in schools (2nd ed.). London, UK: Jessica Kingsley Publishers.

Cite this paper


NerdyHound. (2022, May 22). The Gilliam Autism Rating Scale – 3rd Edition. Retrieved from


NerdyHound. (2022, May 22). The Gilliam Autism Rating Scale – 3rd Edition.

Work Cited

"The Gilliam Autism Rating Scale – 3rd Edition." NerdyHound, 22 May 2022,


NerdyHound. (2022) 'The Gilliam Autism Rating Scale – 3rd Edition'. 22 May.


NerdyHound. 2022. "The Gilliam Autism Rating Scale – 3rd Edition." May 22, 2022.

1. NerdyHound. "The Gilliam Autism Rating Scale – 3rd Edition." May 22, 2022.


NerdyHound. "The Gilliam Autism Rating Scale – 3rd Edition." May 22, 2022.


NerdyHound. 2022. "The Gilliam Autism Rating Scale – 3rd Edition." May 22, 2022.

1. NerdyHound. "The Gilliam Autism Rating Scale – 3rd Edition." May 22, 2022.


NerdyHound. "The Gilliam Autism Rating Scale – 3rd Edition." May 22, 2022.