pub fn friedman(data: &[&[f64]]) -> Option<FriedmanResult>Expand description
Friedman test for k treatments across n blocks (e.g. classifiers × datasets),
data[block] of length k (the measurements, higher = better). Ranks within
each block (ties averaged), then tests whether the treatments differ. None if
fewer than 2 blocks / 2 treatments or ragged input.