| Quartiles
are used to demonstrate the thematic layers on CultureMap.
Quartiles are built by rating every super
output area in London on a measure and then splitting them
into four equal sized groups depending on where they rank
(i.e. each contains the same number of SOA's).
When you select a thematic layer you get a
spread of different shades of blue across the map. There are
four shades of blue in a layer and each of these represents
a quartile.
So taking the example of deprivation, if an
area is colured in the lightest blue it is one of the 25%
least deprived areas and if it is in the darkest blue it is
one of the 25% most deprived areas. An example of the legend
item for deprivation can be seen on th right.
For other thematic layers the legend item
may present the quartiles as percentages. It should still
be noted that 25% of the areas fall into each of the four
categories (see right).
This technique allows different areas to be
quickly and easily compared. |