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UNIT 2 STRENGTHS AND WEAKNESSES OF DATA PRESENTATION
Technique Use Strengths Weaknesses
Field sketches and photographs  For anything you want an  Good memory tool, especially  Only show one view, at one
image of. if accompanied with detailed point in time.
annotations.  May not be an accurate
representation of the area.
Sketch maps  When a rough map of the  Good memory tool, especially  May not be an accurate
study site is needed. if accompanied with detailed representation.
annotations.
Maps with proportional symbols  Bars, pies and symbols can  Good visual representation of  The scale needs to be right so
be used and located in the data. the symbol fits.
relevant place.
Flow lines, desire lines and trip lines  Flow line – represent  Good to show direction (all)  Maps lack precise
movement along a given and size of movement (flow). interpretation unless statistical
route. Variable width along a  They are able to give a good data is added (flow).
given route. visual impression of  Desire and trip lines are only
movement (flow). interested in source and
 Desire/trip lines – straight destination areas, there will
convergence from a central
line on a map to represent the
location. Could be improved
movement of goods and by altering width according to
people from region to region data.
(not a specific route)
Choropleth maps  Often used for land values,  Visually effective, you can see  The whole of an area with
population densities and crop clear spatial patterns. one shading pattern appears
yields, but are useful for a to have the same density with
no variations in it, but in reality
wide range of data.
this is not usually the case
and there will be variations
 Often done using colours, but
within each area.
can be don using lines in
 They give the impression that
different directions. the density changes abruptly
at the boundary line of each
area butt his will not happen
in reality and changes are
more likely to be gradual and

2.
to bear little relation to the
boundary lines.
 With line shading it’s difficult
to draw lines accurately and
it’s time consuming. With the
colouring method, the shades
of colouring are difficult to
achieve, especially with a
large number of classes
unless more than one colour
is used.
Isoline maps  Can be used for any data set  Data can be represented  Can be difficult to construct.
where there are specific without artificial area  There is some element of
locations. boundaries. Therefore guess work involved in the
changes in value occur positioning of the isolines
 Examples are contour maps, smoothly and not abruptly. between values. This makes
meteorological maps  This makes maps useful for them rather subjective,
interpreting general trends in especially if there is a lack of
(isotherm - temperature,
distribution. known values.
isobar - pressure, isohyets -
rainfall and isohel - sunshine)
Dot maps  Mainly used for population  Good visual representation of  Lacks precise location and
distributions, but can also distributions. value of each individual item.
show crop yields, livestock  Allows the major features of a  Too many dots will fail to be
and mineral distributions. distribution to be shown. useful as they will all merge
into one or too few and it will
create the impression of
emptiness.
 Regular spacing of the dots is
extremely difficult to achieve,
as is accurate counting.
 Areas can be missed out if
they don’t conform to the
scale.
 Will only indicate general
variations between areas.
Line (arithmetic) graphs  Show changes over time or with  Can compare multiple  Only to be used with
distance. continuous data sets easily continuous data.
 Interim data can be inferred

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 Smooth line when changes are from graph line.
gradual or straight line to
emphasise changes
Long-sections and cross-sections  Often used in relation to  Long sections show a view of  Either section is more useful
rivers. the whole length. when the other is available.
 Cross sections show a view of  Only a snapshot in time.
a segment.  As it is mostly used for rivers
in Geography, it is ahighly
susceptible to weather and
geological conditions.
Bar graphs  Useful for absolute values and  Good visual representation of  Graph categories can be
contrasts between areas and statistical data. reordered to emphasize
places.  Simple to construct and easy certain effects
to understand.  Use only with discrete data
 Limited space for labelling
with vertical bar graphs
Scattergraphs  Used to compare two sets of  It will show you a correlation  Too few datapoints can
data. between two data sets produce skewed results,
 Often used in combination  Relatively easy to construct. producing in correct graph
with Spearman’s rank.  Shows data spread clearly analysis
and any anomalies stand out.  Impossible to label data
points, hard to ascertain exact
values
 Too many data points can
quickly make graph
unreadable
 Cannot show relationship
between more than two
variables at once
Pie charts  Useful for %’s, statistical data.  Shows % of each segment.  Too many segments make the
 Easy to draw. graph cumbersome.
 They can be used to  Calculation of the amounts is
represent a wide range of more difficult than the bar
statistical data and are chart
visually very effective, as the  If there are a lot of small
contribution of each segment segments then they are
is easy to see. difficult to analyse.
 No exact numerical data.

4.
 Hard to compare 2 data sets.
 "Other" category can be a
problem.
 Total unknown unless
specified.
 Best for 3 to 7 categories.
Triangular graphs  Show the relationship  Show relative importance  Data must be in %.
between three different which may not be easily  Can be difficult to read and to
components. apparent form a data table. construct.
 Shows clusters.
 The dominant component in
each case can be seen.
Kite diagrams  Used to show percentage  allow you to view how much  can be tricky to construct and
change with distance. of each species is there and analyse accurately.
where they are in relation to
each other in a chart format
Radial diagrams  Good when one variable is a  The advantage of radial  These graphs have a limited
directional feature. diagrams in that they allow use and can only be used with
you to display several specific types of data, as the
independent variables. scale around the edge must
be of a continuous nature.
Logarithmic graphs  Large data sets or when the  Very useful when a large  Can be difficult to construct
rate of change is more range of data needs to be and analyse.
important than the actual presented.
amount.
Dispersion graphs  Shows a range of values in a  Visually effective as the full  Data must be in a form which
data set. range of data can be seen can be placed along a number
together with the patterns and line.
groupings of the data.
 Particularly useful for making
comparisons either between
areas or at the same location
over a period of time.