Each of the values of a series is decreased by K. Which of the following does not hold in the context?

When each observation in a series is decreased by a positive constant K, both the first quartile (Q_1) and the third quartile (Q_3) decrease by K. Because Quartile Deviation is (Q_3 - Q_1)/2, the absolute Quartile Deviation remains unchanged; however, the Coefficient of Quartile Deviation, (Q_3 - Q_1)/(Q_3 + Q_1), does NOT remain unchanged because its denominator decreases by 2K, causing the coefficient to rise.