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A bar chart is a chart with rectangular bars of lengths usually proportional to the magnitudes or frequencies of what they represent.
Sometimes the bars are not proportional, often because the chart didn't start at zero.
Standards about starting a chart at zero are not universal. In some case, starting at zero will show little differences between the bars, such as for stock indexes.
If it doesn't start at zero, that can be misleading. Mathematicians will usually signal any chart that doesn't start at zero, such as by using a squiggly line near the bottom of the y-axis.
The bars can be horizontally or vertically oriented. Sometimes a stretched graphic is used instead of a solid bar.
Example
The following example chart is based on the results of the election for the European Parliament in 2004 and in 1999. The following table lists the number of seats allocated to each party group. The results of 1999 have been multiplied by 1.16933, to compensate for the change in number of seats between those years.
| Group
| Seats (2004)
| Seats (1999) scaled
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| EUL
| 39
| 49
|
| PES
| 200
| 210
|
| EFA
| 42
| 56
|
| EDD
| 15
| 19
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| ELDR
| 67
| 60
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| EPP
| 276
| 272
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| UEN
| 27
| 36
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| Other
| 66
| 29
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A bar chart visualizing the above results of the 2004 election can look like this:
This bar chart shows both the results of 2004, and those of 1999:
See also
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