Focus on Psychometrics. Kappa muddles together two sources of disagreement: tetrachoric correlation is preferable

Res Nurs Health. 1993 Aug;16(4):313-6. doi: 10.1002/nur.4770160410.


When assessing agreement between experts, it is important to distinguish between disagreements that can and cannot be explained by different placing of the boundaries between categories. Cohen's kappa statistic is affected by both types of disagreement, tetrachoric correlation only by the second.

MeSH terms

  • Bias
  • Data Interpretation, Statistical*
  • Mathematics
  • Observer Variation*
  • Psychometrics
  • Reproducibility of Results