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Delete - Last Modified By: BJO at 17/02/2015 10:25:41 AM
Hopefully, this is a blast to the past for each of you (but with some modifications).
Bar charts are useful in visualising categorical data. The basic idea is that a graphic representation of the number of items in a particular category can be easily constructed. For example , if a school wide poll for whether or not school uniform should be compulsory (or not) for boys and girls were given as survey to the students, the data might be as follows:
For Uniform Against Uniform
Girls 131 169
Boys 108 192
NOTE: This representation of data is called a two-way frequency table, where categories of data are at the head of the columns and other categories are also at the start of each row. You will come across these types of tables in other topics in Further Mathematics and they are also used extensively in biostatistics, medicine, marketing, engineering production and many other fields of work
Now, to visualise this data as a bar chart, it would be sufficient to draw a graph, with all the categories on one axis, and the data values on the other:
|0 50 100 150 200
Girls For |**************
Girls Against |********************
Boys For |*************
Boys Against |***********************
Conversely, the categories could be on the other axis:
200| *
| * *
150| * *
| * * *
100| * * * *
| * * * *
50| * * * *
| * * * *
0| * * * * .
Girls For Girls Against Boys For Boys Against