Two judges, A and B, scored 5 contestants in a competition out of 50 marks each, as shown below. Convert each judge's scores to ranks (rank 1 = highest score) and find Spearman's rank correlation coefficient between the two judges.
| Contestant | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|
| Judge A's score | 45 | 38 | 30 | 42 | 25 |
| Judge B's score | 40 | 35 | 32 | 44 | 20 |
Step 1 — Rank Judge A's scores (highest = rank 1). Scores , sorted: . Contestant 1 (45)→rank 1; contestant 4 (42)→rank 2; contestant 2 (38)→rank 3; contestant 3 (30)→rank 4; contestant 5 (25)→rank 5.
Step 2 — Rank Judge B's scores. Scores , sorted: . Contestant 4 (44)→rank 1; contestant 1 (40)→rank 2; contestant 2 (35)→rank 3; contestant 3 (32)→rank 4; contestant 5 (20)→rank 5.
Step 3 — Tabulate both rank columns and find .
| Contestant | Rank (A) | Rank (B) | ||
|---|---|---|---|---|
| 1 | 1 | 2 | −1 | 1 |
| 2 | 3 | 3 | 0 | 0 |
| 3 | 4 | 4 | 0 | 0 |
| 4 | 2 | 1 | 1 | 1 |
| 5 | 5 | 5 | 0 | 0 |
| Total | 2 |
(no tied ranks, so the standard formula applies directly).
Step 4 — Apply the formula, .
Independent check. Three of the five contestants (2, 3, 5) received the identical rank from both judges (), and the other two (1 and 4) merely swapped ranks 1 and 2 — a very small, consistent disagreement, matching a high of rather than a moderate or weak value.
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