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FRM Part I · FRM Exam Part I · Linear Regression

A regression of a bond's yield change (Y, in basis points) on a benchmark yield change (X, in basis points) gives fitted Y = 0.5 + 0.80X. The sample standard deviation of X is 6 bp and of Y is 8 bp. What is the sample correlation between X and Y?

The correlation is 0.60. In simple regression the slope equals the correlation times the ratio of the standard deviation of Y to that of X. Rearranging gives 0.80 times 6 divided by 8, which equals 0.60.

  1. A0.60Correct
  2. B0.80
  3. C1.07
  4. D0.75

Explanation

In simple regression slope = correlation x (sd Y / sd X). So correlation = slope x sd X / sd Y = 0.80 x 6/8 = 0.60. Using 0.80 confuses slope with correlation; 1.07 inverts the ratio (0.80 x 8/6), which is impossible as correlation cannot exceed 1.

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