Page 80 - Module_4_en

Module Figure 18 Graph Showing Stable Pattern
4

Phosphous concentration (ug/1)
150
9-12 December, 2013 100

50

0
1992
1994 1996
1966 1988
1990
Year 1998 2000 2002

Correlation analysis

Correlation analysis assists us in understanding the degree to which variables are related to one another,

but does not show cause and effect. Correlated data are presented on a graph, with one variable on
the Y-axis and the other on the X-axis. A positive correlation is shown when the scatterplot moves
in an upward direction, from lower left to upper right. When variables are negatively correlated, the
scatterplot line will run from the upper left to the lower right. The closer the correlation coefficient is
to +1 or -1, the stronger the relationship between the two variables, and the straighter the line on the

graph.

EXAMPLE: Correlation analysis and the Environmental Performance Index

There appears to be a statistically significant correlation between the Environmental Performance
Index and GDP per capita (Figure 19). This indicates that countries that are more developed tend

also to have higher environmental performance, from a policy perspective. While the trend shows
that wealthier countries tend to have better performance, there is much variation in environmental
performance scores among groups of countries located at both ends of the diagram. This indicates
that among wealthy countries, the wealthier countries do not necessarily have better environmental
performance, and likewise environmental performance varies among poor countries.

78 Monitoring, Data and Indicators