HANDLING ATTENTION POINTS◆ 173
160
140
120
100
80
60
40
20
Index of potato production (1997 = 100)^1997
100 110 120 121
(^135140122)
1998 1999
Year
2000 2001 2002 2003
0
Figure 7.1 Eight main types of chart (and when to
use them)
(a) Vertical bar chart
A (hypothetical) index of US potato production, 1997–2003
Use a vertical bar chart when:
- you have simple over-time data that are not really
continuous, but cover discrete time-periods; - you have other appropriate comparative data where
the labels for each bar are short enough to fit
underneath it.
Don’t use vertical bar charts if:
- the bars in the chart have long data labels, especially
not where you would need to use numbers or a key for
labels to fit anything in the column labels.
Points to watch:
- put numbers inside columns, not on top of them;
- if data is not chronological or in categories with a
fixed order, aim to achieve a numerical progression.