# INTRODUCTION TO MEASUREMENTS AND DISPERSION IN STATISTICS

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In any group of statistical data, the numerical values of the items to a lesser or greater degree.

A statistic calculated to measure the degree in which items vary in numerical values is referred to as a measure of variable or measure of dispersion.

Contents

### Importance of Measures of Dispersion

1. It is used in comparing two or more series with regards to variability.
2. It is used in determining how representative the average to the descriptive measure of the given data.
3. It is used in devising a system of quality control. The extent dispersion gives an indication to the management as to whether variation in the quality of products is due to a random factor or some defection in the manufacturing process.

### The Range

The Range is the simplest measure of dispersion with respect to the concept and computation.

It is the difference between the highest and lowest and is given by;
R = Xn – X

### The Range for Grouped Data

In a frequency distribution, the range is the difference between the upper limit of the class at the upper extreme and the lower limit of the lower extreme of the distribution.

### The Mean Deviation (MD)

The mean deviation or average deviation is the arithmetic mean of the absolute differences between the mean and the individual items in the distribution.