Cambridge International as and a level Economics Ebook

6
Cambridge International AS and A Level Economics

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An eff ective way of considering this form of data is to use 
a level and trend approach. Level is concerned with the 
diff erence between the start year and the fi nal year. Trend 
refers to the year-to-year changes shown in 
Table 2
 above.
So, the following additional points can now be made:
■
Average income rose by 22.4% over the period 2008 to 2013.
■
Average income rose most slowly in 2011. It increased by 
only 1.3 index points or 1.2%.
■
Average income rose most rapidly in 2009 at 8.3 index 
points and 8.3%.
■
The second most rapid rise was in 2012 at 5.7 index points 
or 5.1%.
Data skill 5 – how to interpret economic 
information produced in a visual form
Increasingly, economic information is produced in a visual 
form in the media. 
Figure 2 
contains two examples of bar 
charts. Such representations are particularly eff ective for 
mapping out time-series data. Th
e basic principle is that 
the height of each bar represents the data shown on the 
vertical scale: in this case, tourist arrivals in Mauritius.
Th
e value of bar charts is that it is possible to see at a 
glance changes in the level and trend. 
Figure 2a
shows the 
annual numbers of tourist arrivals over a ten-year period 
from 2003 to 2012. What is quite clear is that the level of 
tourist arrivals has increased over this period. A closer 
examination shows that there was a fall between 2008 
and 2009, that just before that there was the most rapid 
rise and that the numbers were unchanged between 2011 
and 2012.
Figure 2b
adds a further dimension, namely that for 
one year, 2012, it shows that there have been monthly 
variations in tourist arrivals, a point not immediately 
obvious from the annual data alone. Tourist arrivals 
peaked in December and were lowest in June. Th
e actual 
arrivals can easily be read off the vertical scale.
Figure 3
 is an example of a pie chart. Th
e basic 
principle behind its construction is that the respective 
shares are shown by the relative sizes of the slices of 
the pie. Th
ese shares are determined by allocating 360° 
for the overall total – the share of each segment is then 
determined by the following formula:
size of each segment
number in a given segment
overall tota
=
ll
o
×
360
South Africa
9.2%
India
5.7%
Reunion
15.0%
Switzerland
2.7%
Germany
5.7%
Italy
4.1%
France
26.6%
United Kingdom
9.1%
People’s Rep.
of China 2.2%
Other countries
19.7%