Statistics is a mathematical science that involves the collection, analysis and interpretation of data. It is widely used in various fields.
Measure of Dispersion is a measure of how the items are scattered about some average or fixed value.
Range, quartile deviation, mean deviation, variance and standard deviation are the measures of dispersion.
Range of a series = Maximum value – Minimum value
The mean deviation of a statistical data is defined as the arithmetic mean of the absolute values of the deviations of observations from an average (fixed value).
A single value that attempts to describe a set of data by identifying the central position within that set is called the measure of central tendency.
To have some idea of variability in a series, we can obtain a single number called the range of the series. The difference of maximum and minimum values of any series is called the ‘range’ of the data.
The proper measure of dispersion about the mean of a set of observations is expressed as positive square-root of the variance and is called standard deviation.
Variance is a quantity which leads to a proper measure of dispersion. It is calculated as the mean of the squares of the deviations from mean.