association
Kendall's tau
Measure ordinal or monotone association with a rank-based coefficient robust to small samples.
Requirements
- two ordinal or continuous variables
Avoid when
- nominal categories
- need original-unit slope
Formula
τ = (concordant − discordant) / total pairs
Interpretation
tau describes concordance minus discordance among paired observations.
Worked example
Estimate ordinal association in a small sample with many tied ranks.
Open example datasets