CAARS™ 2

Single-Rater Report: The CAARS 2 Single-Rater Report provides detailed results from a single administration. This report includes the rater’s responses and scores for all items and scales, details on how ratings compare to ratings of other individuals of a similar age (and gender if requested), an option to compare scores to individuals with a confirmed diagnosis of ADHD and a list of which scores (if any) are elevated compared to the reference sample.

CAARS 2: The Self-Report and Observer forms include all CAARS 2 items and scales. This form is typically used when comprehensive information is sought, such as an initial evaluation or periodic re-assessment to detect any changes in core and associated features of ADHD.

CAARS 2–Short: This form is useful when a rater has limited time, or when the rater will be asked to complete the CAARS 2 multiple times (e.g., monthly assessment of treatment response, medication trials). It takes less time to complete than the full-length form but is not as comprehensive, as it has both fewer scales and fewer items per scale.

CAARS 2–ADHD Index: This index contains the 12 items from the full-length form that best differentiate individuals diagnosed with ADHD from those in the general population. This index can be used as a screener to determine which individuals are most likely to require a more comprehensive evaluation.​

Reliability:

The CAARS 2 Self-Report and Observer scale scores have excellent internal consistency (median omega coefficient = .94 for Self-Report and .95 for Observer), strong test-retest reliability (median r = .92 for Self-Report and .84 for Observer), and moderate inter-rater reliability (median r = .44 to .54, depending on nature of the relationship), which is expected given the different perspectives from multiple raters. Similarly strong evidence of reliability was found for the CAARS 2–Short and CAARS 2–ADHD Index.

Validity:

Results from confirmatory factor analyses (CFA) provided evidence to support the internal structure of the CAARS 2 scales (5-factor model fit best; CFI ≥ .943, RMSEA ≤ .047, loadings > .400).

Evidence for the relationship to other measures supported the convergence of constructs (median correlations with measures of ADHD and impairment ranged from .48 to .83).

The CAARS 2 demonstrated a high degree of criterion-related validity as various clinical groups had distinctly different profiles of scores (e.g., very large median effect size estimates for the difference between individuals with ADHD and individuals from the general population [Cohen’s d = 2.24 for Self-Report, 1.29 for Observer]), and

scores from the CAARS 2 were able to correctly classify individuals from the General Population and those from clinical samples into their respective groups (overall correct classification statistics ranged from 84.7% to 92.5% across forms).

Fairness:

There is strong evidence that the CAARS 2 meets or exceeds the fairness requirements outlined in the Standards for Educational and Psychological Testing (AERA, APA, & NCME, 2014). When investigating differences by gender, race/ethnicity, country of residence, and education levels, there was (a) sufficient evidence of equivalence of the factor models, (b) no evidence of meaningful differential test functioning between groups, and (c) negligible to small differences in average scores between groups (median Cohen’s d = 0.06 across raters and all group comparisons). The absence of statistical bias and the lack of significant group differences provide strong evidence for the fair use and interpretation of the CAARS 2 scores.

A total of 2,640 individuals were included in the Normative Samples (N = 1,320 each for Self-Report and Observer). Combined gender norms are provided for individuals in the following age groups: 18-24, 25-29, 30-39, 40-49, 50-59, 60-69, and 70+; separate norms for males and females are also available. ADHD Reference Samples are also available (N = 255 for Self-Report and N = 170 for Observer).