CA Foundation · Quantitative Aptitude · Correlation and Regression
For a bivariate data set, the regression coefficient of Y on X is 1.6. Which of the following values CANNOT be the regression coefficient of X on Y for the same data?
The value 0.9 is impossible because the product of the two regression coefficients equals r squared and cannot exceed 1. With byx equal to 1.6, bxy cannot exceed 0.625, and 1.6 times 0.9 is 1.44, which is more than 1.
- A0.25
- B0.5
- C0.6
- D0.9Correct
Explanation
The product of the two regression coefficients equals r², which cannot exceed 1. With byx = 1.6, bxy must be at most 1/1.6 = 0.625. A value of 0.9 gives a product of 1.44, which is impossible. The other three values give products 0.4, 0.8 and 0.96, all valid.
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