Graph Guidelines

Graphs can quickly convey relationships and trends between and among data in ways that a data table or text narrative struggles to achieve.

Each type of graph has a purpose that it is best suited for.

Some have purposes they should never be used for.

Editors who know these principles can more effectively ensure that the graphs suit their intended purpose and fit scientific and mathematical standards for data communication.

This is a round-up of advice and resources explaining the best practices (and some pitfalls) for data presented in graph form.

 

Pitfalls of Graphs

Tweet this post. These are the most common errors made in creating graphs. They can even put your motives into question because they manipulate perceptions so deeply. Avoid these:

  • Exaggerated scale (affects perception of line slope / change over time)
  • Scale doesn’t start at zero (affects perception of scale of change)
  • Type doesn’t suit data (implies relationships that don’t exist)

 

Types of Graphs and Their Best Uses

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Type of Graph Best Uses
Line
graph line plot example
Best Uses: Changes over time (or any continual measure, such as size)

Poor Use: (example) Many people’s test results

Pie / circlepie chart example Best Uses: Compare parts of a whole

Poor Use: Individual percentages or unrelated data, totals more than 100%

Bar
bar graph example
Best Uses: Compare different groups

Poor Use: Changes over time

X-Y / scatter

scatter plot diagram example

Best Uses: Pattern in relationship between variables, with discrete data points

Poor Use: Percentages

Area
area graph example
Best Uses: Compare changes in related groups within a category

Poor Use: Unrealated categories

Variables

Dependent and independent variables and why the difference matters.

Resources

Editing by Design, Jan White, pp. 159–162, 168.

What each type of graph is used for.

Statistics Canada’s guidelines for graphs

See chapters 16 & 17 in Geoff Hart’s Writing for Science Journals 

 

Sources of samples: line graph author’s original, pie chartbar graphscatter plotarea chart

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