## Dispersion

 8.1 Dispersion

 Definition Measures of dispersion are measurement in statistics. It give us an idea of how values of a set of data are scattered.  Dispersion small if the data set are quantitative measures such as range, interquartile range, variance and standard deviation

 Tips The distribution of data is different.  To understand the dispersion of data, the difference between the largest value and the smalles value is taken into consideration. If the difference between the value is large, it indicates that the data is widely dispersed and vice versa.

Example

The table below shows the masses, in $$kg$$ of $$10$$ pupils

 $$52$$ $$62$$ $$12$$ $$9$$ $$8$$ $$75$$ $$44$$ $$33$$ $$19$$ $$16$$

State the difference in mass, in $$kg$$ of the pupils

Solution

Largest mass $$= 75$$

Smallest mass $$=8$$

Difference in mass,

\begin{aligned} &\space = 75-8 \\\\& = 67. \end{aligned}

 Stem and leaf plot It is a way to show the distributions of a set of data.  Through stem-and-leaf plot, we can see whether the data is more likely to appear or least likely to appear.

Steps to plot the stem-and-leaf plot

Given the data is unorganised, for example

 $$52$$ $$33$$ $$25$$ $$38$$ $$53$$ $$53$$ $$35$$ $$25$$ $$53$$ $$49$$

Thus, we cannot see the dispersion immediately. We set the tens digit as the stem and the unit digit as the leaf for the given data.

 Stem Leaf $$2$$ $$5,5$$ $$3$$ $$3,5,8$$ $$4$$ $$9$$ $$5$$ $$2,3,3,3$$

Key $$2|5$$ means $$25$$

 Dot plots It is a statistical chart that contains points plotted using a uniform scale. Each point represents a value

 Example of dot plot

## Dispersion

 8.1 Dispersion

 Definition Measures of dispersion are measurement in statistics. It give us an idea of how values of a set of data are scattered.  Dispersion small if the data set are quantitative measures such as range, interquartile range, variance and standard deviation

 Tips The distribution of data is different.  To understand the dispersion of data, the difference between the largest value and the smalles value is taken into consideration. If the difference between the value is large, it indicates that the data is widely dispersed and vice versa.

Example

The table below shows the masses, in $$kg$$ of $$10$$ pupils

 $$52$$ $$62$$ $$12$$ $$9$$ $$8$$ $$75$$ $$44$$ $$33$$ $$19$$ $$16$$

State the difference in mass, in $$kg$$ of the pupils

Solution

Largest mass $$= 75$$

Smallest mass $$=8$$

Difference in mass,

\begin{aligned} &\space = 75-8 \\\\& = 67. \end{aligned}

 Stem and leaf plot It is a way to show the distributions of a set of data.  Through stem-and-leaf plot, we can see whether the data is more likely to appear or least likely to appear.

Steps to plot the stem-and-leaf plot

Given the data is unorganised, for example

 $$52$$ $$33$$ $$25$$ $$38$$ $$53$$ $$53$$ $$35$$ $$25$$ $$53$$ $$49$$

Thus, we cannot see the dispersion immediately. We set the tens digit as the stem and the unit digit as the leaf for the given data.

 Stem Leaf $$2$$ $$5,5$$ $$3$$ $$3,5,8$$ $$4$$ $$9$$ $$5$$ $$2,3,3,3$$

Key $$2|5$$ means $$25$$

 Dot plots It is a statistical chart that contains points plotted using a uniform scale. Each point represents a value

 Example of dot plot