Gilliam Autism Rating Scale: 3rd Edition

James E. Gilliam, Ph.D.

      Technical Information

      Reliability and Validity

      • Internal consistency (content sampling) reliability coefficients for the subscales exceed .85 and the Autism Indexes exceed .93.
      • Test-retest (time sampling) reliability coefficients exceed .80 for subscales and .90 for the Autism Indexes.
      • Interrater reliability intraclass coefficients exceed .80 and .84 for the Autism Indexes.
      • Correlations of the GARS-3 scores with those of other well-known diagnostic tests for autism are large or very large in magnitude.
      • All new validity studies show that the test results are valid for a wide variety of subgroups, as well as for the general population.
      • Binary classification studies indicate that the GARS-3 is able to accurately discriminate children with autism spectrum disorder from children without autism (i.e., sensitivity = .97, specificity = .97, ROC/AUC = .93.
      • Confirmatory and exploratory factor analyses demonstrate the theoretical and empirical validity of the subscales.
      • Other validity evidence is provided in the manual.


    Author James E. Gilliam

    Age Range 3 through 22

    Administration Time 5 to 10 minutes

    Administration Type Individual