• CAARS 2 (Full-Length)
• CAARS 2–Short
• Percentiles

This appendix provides the 90% and 95% confidence intervals (CIs) for all T-scores by scale for the Conners Adult ADHD Rating Scales 2nd Edition (CAARS™ 2) forms as well as the standard score to percentile conversion table for the ADHD Reference Sample.

The online scoring automatically includes the confidence interval based on the Normative Samples for every T-score; however, the user can choose whether to use 90% or 95% confidence intervals (see chapter 3, Administration and Scoring, for details on scoring options).

The confidence intervals for the ADHD Reference Sample can be obtained by referencing Tables C.1 to C.4 in this appendix. The confidence interval for a given T-score can be determined by following these steps.

Begin by finding the CI value as follows:

1. Find the correct table, based on
   
   
   1. the length of the form (full-length CAARS 2 or CAARS 2–Short), and
      
      
   2. the rater (Self-Report or Observer).
   
   
2. Select the appropriate column in the table, based on
   
   
   1. the level of confidence to be used (90% or 95%), and
      
      
   2. the gender used for scoring (Combined Gender, Males, or Females).
   
   
3. Find the row that contains the scale.
   
   

Once you have the correct cell, calculate the CI as follows:

4. Calculate the Lower Bound of the CI by subtracting the CI value from the obtained T-score.
   
   
5. Calculate the Upper Bound of the CI by adding the CI value to the obtained T-score.
   

For example, on the full-length CAARS 2, Observer form, using the Combined Gender ADHD Reference Sample, the Impulsivity T-score was 72. To determine the 90% CI for this score, the interpreter refers to Table C.2. The interpreter selects the “Combined Gender” column, using the left set of values for 90% CI. The CI value of 5 is found in the Impulsivity row. The CI is then calculated as follows:

• Lower Bound: 72 – 5 = 67 (i.e., obtained T-score minus the CI look-up value)
  
  
• Upper Bound: 72 + 5 = 77 (i.e., obtained T-score plus the CI look-up value)
  

This process produces the 90% CI of 67-77 around the ADHD Reference Sample T-score of 72 on this CAARS 2 Observer Impulsivity scale.

CAARS 2 (Full-Length)

CAARS 2–Short

Percentiles

The percentiles for the ADHD Reference Sample can be obtained by referencing Table C.5 in this appendix. The percentile for a given T-score is located to the right of the T-score (see chapter 7, Standardization, for details on the creation of T-scores and percentiles; see also appendix E for interpretation guidelines).