As well as frequency tables, data can be displayed in a a variety of graphs and charts too.
Three of the most common are Line Graphs, Bar Graphs and Pie Charts.
The frequency table below shows how many hats a clothing store sold over 5 days.
|Day        ||Hats Sold    |
This can be presented with a line graph.
The first step is to draw up a standard axis like a positive x and y axis on a Cartesian plane.
Usually the numeric values being counted or measured makes up the vertical axis on the left, and the categories make up the horizontal axis.
Here we have set up a suitable scaled axis for the information in the hats sold table.
Next step is to place points at the right number for each category. So here it's the right number of hats sold for each day.
Then to complete the line graph, we draw a line from point to point, connecting them up.
The hats sold data can also be displayed in a bar graph.
A Bar Graph is similar to a line graph in principle. We again set up a suitable axis, then draw vertical bars as high as each number of hats sold for each separate day.
Double Bar Graphs are handy when you want to compare two different amounts.
Below is a table of annual rainfall in milimetres for the years 2011 and 2012, in 3 different cities.
|CITY    ||2011 Rain    ||2012 Rain    |
A double bar graph here, will have 2 different bars for 2011 and 2012, in each separate city.
Along with line graphs and bar graphs, another common method for displaying data is in a pie chart.
As the name suggests, this is a chart that is circular in shape.
We can create a pie chart with data regarding how many TVs each person owns in a group of 20 people.
|Number of TVs    ||People who own        |
The whole group is 20 people, this is 100% of the group.
Each smaller group that owns a certain number of TVs, will be a part of this 100%.
As a pie chart is a circle, the different categories are sectors of a circle.
A whole circle is 360°, and this 360° represents 100% of the group, all 20 people.
There are 5 categories, so the pie chart will have 5 separate sectors, each representing a different group of TV owners.
What we want to know, is the size of each different sector.
Each sector for each category will make an appropriate angle that is part of 360°.
Depending on what percentage of the larger group of 20, the category is.
Owner of 1 TV   =>    × 360°   =   0.1 × 360°   =   36°
Owner of 2 TVs   =>    × 360°   =   0.35 × 360°   =   126°
Owner of 3 TVs   =>    × 360°   =   0.15 × 360°   =   54°
Owner of 4 TVs   =>    × 360°   =   0.25 × 360°   =   90°
Owner of 5 TVs   =>    × 360°   =   0.15 × 360°   =   54°
If the sums are right, the smaller angles should add up to 360°.
36° + 126° + 54° + 90° + 54°  =  360°
So we're good to proceed with making the Pie Chart.
To start with, draw a vertical radius line to the centre of the circle, then measure the first angle in a clockwise direction, drawing another radius line at the correct place for the size of this first angle.
Then for the next sector, begin measuring the next angle again from this new radius line.
Continue this process until completing a full circle, then the pie chart will be complete.