## Quartile Deviation calculator for ungrouped data

Quartile Deviation for ungrouped data Quartile deviation (QD) is an absolute measure of spread or dispersion based on the quartiles. Quartile deviation is defined as half of the distance between the third quartile $Q_3$ and the first quartile $Q_1$. It is also known as semi-interquartile range. Thus the quartile deviation is given by \$QD = …