Reciprocal Rank Fusion

Reciprocal rank fusion | Elasticsearch Guide 8.13 | Elastic $score_i = {1\over a_i} + {1\over b_i}$

• Same as harmonic mean for large and small relationships
• $k$ may be added
  • 
    • Reciprocal Rank Fusion outperforms Condorcet and individual Rank Learning Methods(PDF)
    • Here k=60
  • Increasing k reduces the difference between first and second place.

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