For testing independence, show that X² ≤ n min (I – 1, J – 1). Hence V² = X² / [n min(I – 1, J – 1)] falls between 0 and 1 (Carmer 1946). For 2 × 2 tables, X² / n is often called phi-squared; it equals Goodman and Kruskal’s tau. Other measures based on X² include the contingency coefficient [X²/(X² + n)]^1/2 (Pearson 1904).