Using graphical data
Dr Michelle Reid
Study Adviser, University of Reading
Overview of the workshop
• Why use graphical data?
• Tables, graphs, diagrams, pictures
• What to remember when using graphical data
To start you thinking…
Who writes reports?
Working in pairs:
• List as many different kinds of reports as you can
(e.g. Reports on lab work, reports on field work)
A prize for the longest list!
Why use graphical data?
• Shows information in an easy to understand visual
form
• Adds value – conveys something more than just
writing can
• Helps the reader see trends, patterns, or complex
processes more easily
• Is accurate, relevant, and clear – and has a purpose
Referring to graphical data
• If you include a figure or table, you should always
refer to it and explain what it shows:
e.g. “The Keeling plant's production capacity was
reached in May this year. In contrast, the Hergort
plant has not yet reached 75% of its production
capacity (see Table 13)”.
• Label your figures clearly – figure 1, figure 2, etc
• Make it clear to your audience which one you are
referring to
Main types of graphical data
• Tables
• Bar charts
• Line graphs
• Pie charts
• Drawings / diagrams
• Photographs
Tables are useful for…
• Presenting a quantity of numerical data in
an accessible format
• Showing exact numbers
Using tables
• If you have a lot of data in tables – are they all
essential? Can some be placed in an appendix?
• Make sure your columns and rows are clearly labeled
• Tables can rarely stand alone – you need to describe
in words what the table shows – what are the key
things the reader should look for?
• Graphs may be better for showing trends or patterns
Bar charts are useful for…
• Comparing discrete values or categories
• Comparing a number of different discrete values side
by side (see fig.2)
Internet use by Redwood School students
1995-2002
Figure 1
Figure 2 (From Statistics Canada)
Using bar charts
• Bars can be vertical or horizontal (horizontal is
sometimes best if there are a lot of categories)
• Use of colours can help distinguish between the bars
• Bar charts are not as effective as line graphs at
showing continuous increasing / decreasing trends
Line graphs are useful for…
• Showing trends (how data changes over time)
• Showing relationships (how two variables interact)
Using line graphs
•
Check that your values for the x-axis (horizontal)
and the y-axis (vertical) are correct
•
When plotting trends over time, the x axis is
commonly used to represent units of time, and the
y axis is used to represent quantity
•
Use a sensible scale so that the line’s shape does
not give the audience an incorrect impression of
the data
Line graph scales
Number of guilty crime offenders, Grishamville, 2007
Figure 1
Which scale gives the
most accurate view of
the trend in offender
reduction?
Figure 2
Graphs from Statistics
Canada
www.statcan.gc.ca
Pie charts are useful for…
• Showing the percentage or proportion of the whole
that is taken by various parts
• percent ÷ 100 x 360 degrees = the number of
degrees
Using pie charts
• Put the %s in as numbers alongside the segments for
ease of reading
• The chart can become difficult to read if there are
too many segments
• Avoid using a pie chart if you have a lot of small %
which are very similar – the segments will be hard to
distinguish
• When comparing two sets of data (e.g. figures for
boys and girls) use a double bar graph, as comparing
segments across two separate pie charts is difficult
Drawings / diagrams are useful for…
• Showing complex
processes or detailed
technical descriptions
• Showing a step-by-step
cycle or process (e.g. in
manufacturing)
Diagram by Eric Pierce
Using drawings / diagrams
• Make sure all your diagrams are large enough and of
sufficiently high quality
• Label and explain each diagram fully
• Reference any diagrams / figures that have been
created by another person
Photographs are useful for…
• Illustrating what is being described
• As visual evidence (e.g. showing a particular site,
scene or landscape)
• When you need “real world” visual evidence, that
can’t easily be drawn
Photo by K. Kiser
Using photographs
• It is tempting to include photos just to make your
report look nice! Always think - what is the purpose
of this photo and what would happen if it wasn’t
there?
• Reference all photos taken by another person
• You may still have to ask permission to use your own
photos if your work is likely to be published (e.g. if it
is of people or a private building etc)
• Check the quality, especially if you are printing colour
photos in black and white
Activity: What’s wrong with this picture?
Working in small groups – each group has a different
image / graph
Assess the use of graphical data – is your figure:
•
•
•
•
Appropriate
Clearly labelled
Accurate
The right scale
Why has this form of graphical data been chosen?
What to remember when using graphical data
 Is this necessary, or just decorative?
 Have you double checked the data for accuracy?
 Is the type of figure (graph / table / diagram) appropriate for
its purpose?
 Is the figure labelled clearly with a title?
 Does it have a key if necessary?
 Is the figure of sufficient size and quality to be easily
interpreted?
 Do you describe what the figure shows in words too?
 Have you referenced all figures created by other people?
Further resources
LearnHigher report writing webpages
www.learnhigher.ac.uk/learningareas/reportwriting/home.htm
Guides and exercises on all aspects of reports.
Analyse this! (Manchester Metropolitan)
www.learnhigher.ac.uk/analysethis/
Simple and accessible guide to data analysis
Any questions?
Thank you and good luck with your report
writing!