How to work with graphs and charts
Types of graphs and charts
Graphs and charts are used to present data visually with the intention of making the information easy to
understand. While this is an advantage over figures and tables, it can also be a major disadvantage, as
graphs and charts can be manipulated quite easily.
There are various types of graphs and charts. The most common ones are line graphs, bar charts and pie
charts.
Line graph
A line graph is mostly used to show development in amounts over a period of time. It
is especially useful for comparing the development of two (or more) figures or
variables.
Bar chart
Like a line graph, a bar chart can also show development in amounts over a period of
time. I can also reveal differences between various elements at one time or over a
period of time.
Pie chart
A pie chart consists of a circle (pie) divided into sections/sectors/segments that
represent parts of the whole. The parts are usually shaded, and a key explains what
the parts represent.
Approaching charts
It is useful to analyse charts using the following steps:
1. orientation
2. description
3. explanation
4. evaluation
In the course of the analysis you should ask yourself the questions below. Naturally, not all the questions
listed below need be taken into consideration. The choice of questions to be considered depends on the
type of chart you are working with.
1. Orientation
- What is the subject of the chart? Here the title should help you.
- What type of chart is presented?
- What period of time is covered?
- What figures are used: absolute figures (i.e. numbers) or relative figures (i.e. percentage figures)?
- Where does the chart come from? (The source is usually given next to the chart.)
- When was the chart first published? Is it still topical? If not, is this a problem, or is the chart still
useful for your purposes?
2. Description
- What facts does the chart provide?
Never just read out figures, but rather work with them by:
o pointing out developments;
o showing extremes (e.g. peaks and low points).
- Can the chart be structured (i.e. divided into periods which show contrasting, similar, etc.
developments)? (A chart is not so different from a written text as you might think.)
3. Explanation
- If possible, refer to the historical, social, political, economic developments which could help to
explain the chart’s message.
4. Evaluation
- Do the title and the contents of the chart match?
- Does the chart try to manipulate the reader (e.g. how are the time intervals on the x-axis spaced?
Do the intervals on the x-axis differ from those on the y-axis)?
