Range is defined as the difference between the values of the largest and the smallest observations.
Range = Maximum value - Minimum value.
The range of a data given us a rough idea of variability; but does not tell us about the dispersion or deviation of the data from the central values (mean, medium and mode).
The range in this case tells us nothing about the heights of seven other people in the group or their dispersion from the mean height.
Merits and Demerits of Range
- It is simple to calculate and understand.
- It is only based on the smallest and the largest values and gives only a rough idea about dispersion.
- The other values (other than the largest and smallest) have no effect on range.
- The value of range is affected by extremely high or low values of the top and bottom values.
For the set of observations 13, 25, 36, 22, 18, 45, 21, 26, 30, 22 find the range.
This is calculated by finding the first quartile (Q1) and third quartile (Q3) or lower and upper Quartiles.
Quartile deviation =
[This is not mentioned in the syllabus and so we are not going into the detail]