Question

Which of the following is not a measure of dispersion or variability in a set of data?

	a.	range
	b.	average of the lowest and highest observations
	c.	standard deviation
	d.	interquartile range

Answer 1

Answer - option (b) average of the lowest and highest observation.

Firstly we need to know the meaning of dispersion which is Dispersion is a statistical term that describes the size of the distribution of values expected for a particular variable.

Measures of dispersion are -

There are two main types of dispersion methods in statistics which are- 1) Absolute Measure of Dispersion 2) Relative Measure of Dispersion.

Absolute dispersion method expresses the variations in terms of the average of deviations of observations like standard or mean deviations. It includes range, standard deviation, quartile deviation, etc. On the other hand,

Relative measure of dispersion are the relative measures of depression are used to compare the distribution of two or more data sets. This measure compares values without units, some e.g. are Co-efficient of Range, Co-efficient of Variation, Co-efficient of Standard Deviation.

Therefore, Range, interquartile range, standard deviations are clearly the measure of dispersion or variability in a set of data.

The only option (b) average of the Highest and lowest observation is not the measure of dispersion.

Mean deviation is different from this, The average of numbers is known as the mean and the arithmetic mean of the absolute deviations of the observations from a measure of central tendency is mean deviation. Rest options are not correct because they are the measure of dispersion.

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