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Exercises · Q7
Q.

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.

Contestant12345
Judge A's score4538304225
Judge B's score4035324420
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✓ Free question

Step 1 — Rank Judge A's scores (highest = rank 1). Scores 45,38,30,42,2545,38,30,42,25, sorted: 45>42>38>30>2545>42>38>30>25. 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 40,35,32,44,2040,35,32,44,20, sorted: 44>40>35>32>2044>40>35>32>20. 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 d,d2d, d^2.

ContestantRank (A)Rank (B)ddd2d^2
112−11
23300
34400
42111
55500
Total2

∑d2=2\sum d^2=2 (no tied ranks, so the standard formula applies directly).

Step 4 — Apply the formula, n=5n=5.

rs=1−6×25×24=1−12120=1−0.1=0.9r_s = 1-\dfrac{6\times2}{5\times24} = 1-\dfrac{12}{120} = 1-0.1 = 0.9

Independent check. Three of the five contestants (2, 3, 5) received the identical rank from both judges (d=0d=0), and the other two (1 and 4) merely swapped ranks 1 and 2 — a very small, consistent disagreement, matching a high rsr_s of 0.90.9 rather than a moderate or weak value.

✓Final answer

rs=0.9r_s = 0.9.

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