Data Visualization Tips

Data Visualization Tips#

Time Series Clarity#

  • Display dates/time frames on the x-axis in ascending order (unless there’s a specific reason not to). This ensures intuitive trend interpretation.

Label Everything#

  • Always label axes and include units (e.g., “Percentage (%)” or “Population (thousands)”).

  • Define variables and terms in captions or legends (e.g., clarify if “46.0” represents people, percentages, or scaled values).

Title & Context#

  • Use clear, descriptive titles that specify the metric and relevant information about the dataset (e.g., “Mean Household Income (2020–2024)” instead of “Income Trends”).

  • Indicate whether values are sums, means, medians, etc. (e.g., “Median Wait Times for Emergency Care”).

Plot Type Selection#

  • Line charts: Trends over time

  • Bar charts: Category comparisons

  • Boxplots/Violin plots: Distributions

More details about each chart type are discussed in this section by Statistics Canada: Data Visualization

Design Best Practices#

  • Use consistent colours/legends across plots to aid comparison.

  • Annotate key trends (e.g., “Peak in 2021” with an arrow).

  • Avoid clutter: Split complex data into multiple plots.

Avoid Misleading Scales#

  • Start y-axis at zero unless justified (e.g., log scales). If truncated, explain why in the caption.

Accessibility#

  • Ensure colour choices are colourblind-friendly (tools: ColorBrewer).

  • Use patterns/textures in addition to colours for B&W printing.

Normalization for Comparisons#

Normalization removes scale differences, letting viewers focus on relative changes.

  • When to normalize:

    • If the main goal is to compare trends or patterns (not absolute values), scale values to a common range (e.g., 0–1 or 0–100%).

  • How to label:

    • Clearly state the normalization method in the axis/caption (e.g., “Values normalized to 2015 baseline (=100%)” or “Percent of total group”).

  • Caveats:

    • Avoid normalization if absolute values matter (e.g., budget allocations in dollars).

Examples#

Infographic: Building Permits in Canada#

It’s important to include clear elements such as a title, map, explanation, and tables or summary boxes. These elements help ensure your message is easy to understand at a glance.

The infographic below summarizes building permits in Canada for April 2025:

Notice how it uses a combination of:

  • Title: Clearly states the topic and time period.

  • Map: Visualizes geographic differences across provinces and territories.

  • Explanations: Uses colour, arrows, and percentages to highlight changes.

  • Tables/Summaries: Breaks down the data into categories (residential, non-residential) and uses icons for quick interpretation.

  • Source: Properly cites the data source at the bottom.

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