Krippendorff's Alpha

A statistical measure of inter-rater agreement used to assess how consistently two or more coders classify the same qualitative data. Developed by Klaus Krippendorff, the metric handles any number of coders, any level of measurement (nominal, ordinal, interval, ratio), and missing data, and corrects for agreement expected by chance. Values range from -1 to 1, with 1.0 indicating perfect agreement, 0.0 indicating chance-level agreement, and conventional thresholds of 0.667 for tentative conclusions and 0.800 for reliable results. Krippendorff's alpha is widely reported in accessibility and HCI research to demonstrate the reliability of thematic analysis, content coding, and qualitative studies of disability experiences.