When writing about topics related to data or numbers in general it’s often more impactful to display the data in a figure, graph, or chart than to simply discuss the main ideas and relationships. The type of data you’re working with will dictate the formats available. There are many options and different conventions depending on your discipline, but here are some basic guidelines based on what you hope to show:
Showing a relationship – A basic x-y scatter or line plot will show trends between variables.
Showing a comparison – Column or bar charts will easily compare values in distinct categories, while line plots or bar charts can show how a variable evolves over time.
Showing a distribution – Histograms, either column or line, can show how a single variable is distributed. Scatter plots are often a good choice for single variables.
Showing composition – Stacked columns charts will easily show how different parts make up a whole.
Once you’ve picked the most useful type of figure, there are a few key points to keep in mind:
- Keep in-figure text to a minimum and make sure it’s easily readable.
- The caption should start with a sentence or title that makes the importance of the figure clear, and the following description should allow the figure to make sense if viewed without the text.
- Make the data the focus, avoiding unnecessary art or illustration.
- Avoid using 3D plots or charts. While they may show more information, 3D plots are usually difficult to understand.
- Intentionally choose colors to either clarify relationships or support some theme, but keep in mind that the contrast should allow for easy reading. Make sure color selection is legible for those with colorblindness (i.e. don’t use red-green or yellow-blue combinations).
- Don’t include unnecessary lines like gridlines or excessive tick marks.
- Make sure that all your decisions are intentional and support the message the figure is intended to convey.
If you’re having trouble deciding on what kind of figure you need, you might turn to this discussion of tables and charts.