Effective Data Storytelling
Presenting a single number is baseless for your audience. The way the human brain works is to use reference. Comparison is crucial in data storytelling because it helps provide context, identify patterns, and highlight relationships between different data points or variables.
Here are some key benefits of using comparison in data storytelling-
- Contextualize data:
Your audience can resonate data to real-life questions like “Is the current value high or low?”, “Is it better or worse than previous periods?”, these questions help provide a clearer understanding of the data’s significance. - Identify trends and patterns:
By comparing data across different time periods or groups, you can identify trends and patterns, especially for time series data. For example, comparing sales data month over month or year over year can reveal whether sales are increasing or declining. Such comparisons help to identify patterns, make predictions, and inform decision-making. - Support arguments and storytelling:
Comparison is an effective way to support arguments or tell a compelling story with data. By comparing data points, you can illustrate cause-and-effect relationships, support hypotheses, or showcase the impact of certain factors. It adds depth and credibility to your narrative, making it more persuasive and engaging for the audience.
Given “comparison” is so useful, how to use comparison in data storytelling?
Here are 5 major ways, and let’s go through them one by one with illustrated examples.
- Use Baseline
Data transformation against baseline can quickly create a comparison view for easily observing units that are above or below the baseline.
We are visualizing sales revenue for each month for the last year, there are some highs and some lows across the months. One useful question is “how each month performs compared to the monthly average?”
An analytical tool should provide a one-click shortcut to transforming the view from a raw month-by-month revenue view to this percentage increasing or decreasing value to understand each month’s sales performance.
2. Use Pivot
Many people are familiar with pivot tables in Excel. Pivoting is powerful as it provides comparing the view of one dimension while observing from another dimension.
Pivoting result usually provides side-by-side comparison organized into groups. The dimensions used in pivoting keys should be categorical values.
We are analyzing student scores by looking at their study group and genders. Query: average score by group + gender.
3. Use Threshold
A threshold defines a visual difference for values above or below a “threshold” value. It’s usually used with a Line plot for a visually appealing look and feel. Unlike baseline transformation and dimension pivoting which are data manipulations, the threshold is purely visual manipulation of the same data.
Continuing with the student scores analysis. Let’s pull the median value for each week, and define a threshold to see which weeks are above the threshold or which ones are below.
4. Use Highlight
Highlight is another visual manipulation, it creates a visual comparison by marking some specific values outstanding out of all.
Highlighting is usually used to emphasize a specific value to make the story more focused on it.
When we analyze the annual average CPI year over year in the US, we noticed there are a few years spike out, can’t stop to highlight and mentioning them, especially the year from 1916–1920 during the great depression.
Here we used two visual highlight technicals:
- Highlight specific bars to call them out using a different color.
- Highlight a specific range by putting a shade over it.
These highlights successfully attract readers' eyes to help them quickly realize those special years.
5. Use a Comparison Chart
Some data chart type is created for comparison purpose, so if your data falls into that category, using them will effectively convey the difference to your audience.
For example, Pie charts or Doughnut charts, are designed for comparison, to illustrate how much “portion” a slice is taking…
Summary
Comparison is a very useful technique in data storytelling that helps you convey your points of view on your data effectively. Please choose a tool that enables these functions in a simple intuitive way.
Happy data storytelling!
References
- Transform data using baseline: an example.
- Pivot data on multi-dimensions: an example.
- Use Threshold with a line: an example.
- Highlight and shade: an example.
- Comparison chart: an example.
