For a given set of pair data, the correlation and regression coefficients have been calculated as being equal to r, byx and bxy respectively. Now, each of values in the x series is divided by 4. What effect does it have on each of their coefficients?
β Correct Answer: There is no change in r but byx changes to 4byx and bxy changes to bxy/4.
π Explanation:
We have a dataset where:
- rr = Correlation coefficient
- = Regression coefficient of Y on X
- = Regression coefficient of X on Y
Now, each value in the x-series is divided by 4. Let’s analyze the effect.
1. Effect on Correlation Coefficient (r)
- The correlation coefficient (r) is a unit-free measure of the relationship between X and Y.
- Scaling X by dividing by 4 does not affect r.
πΉ Conclusion: rβ² = r
2. Effect on Regression Coefficient (Regression of Y on X)
The formula for is:
- Οx (standard deviation of X) is divided by 4, so the denominator decreases by a factor of 4.
- Since division in the denominator leads to an increase in value, is multiplied by 4.
πΉ Conclusion:
2. Effect on Regression Coefficient (Regression of X on Y)
The formula for is:
bxy = [r Γ Οx] /Β Οy
- Since is divided by 4, the numerator decreases by a factor of 4.
- This means is divided by 4.
πΉ Conclusion:
β Final Answer:
| Coefficient | Effect |
|---|---|
| rΒ (Correlation Coefficient) | No Change |
| (Regression of Y on X) | Multiplied by 4 |
| (Regression of X on Y) | Divided by 4 |