Reliability of the ADI-R: Multiple Examiners Evaluate a Single Case

The authors assessed the reliability of the Autism Diagnostic Interview (ADI-R). Seven Clinical Examiners evaluated a three and one half year old female toddler suspected of being on the Autism Spectrum. Examiners showed agreement levels of 94–96% across all items, with weighted kappa (K_w) between .80 and .88. They were in 100% agreement on 74% of the items; in excellent agreement on 6% of the items (93–96%, with K_w between .78 and .85); in good agreement on 7% (89–90%, with K_w between .62 and 0.68); and in fair agreement on 3% (82 – 84%, with K_w between .40 and .47). For the remaining 10% of ADI-R items, examiners showed poor agreement (50–81% with K_w between −.67 and .37).