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CA Foundation · Quantitative Aptitude · Correlation and Regression

A student applying the concurrent deviation method to a data set with N = 12 pairs of deviations finds c = 9. Which statement about the result is correct?

Here 2c − N = 18 − 12 = 6 is positive, so r_c = +√(6/12) = +√0.5 ≈ 0.707. The series show positive association, because c is greater than N/2.

  1. Ar_c = +√0.5 and the series show positive associationCorrect
  2. Br_c = −√0.5 and the series show negative association
  3. Cr_c = +0.5 exactly
  4. Dr_c = 0 because c exceeds N/2

Explanation

2c − N = 18 − 12 = 6, which is positive, so the sign is positive. r_c = +√(6/12) = +√0.5 ≈ 0.707, indicating a fairly strong positive association. Since c exceeds N/2, correlation is positive, not zero; it would be zero only if c = N/2.

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