Data Visualization

Present data so users reach correct conclusions faster. Bad visualization misleads; good visualization reveals.

Chart Selection Matrix

Match the chart to the question, not the other way around.

Question	Best Chart	Avoid
How does this change over time?	Line chart	Pie chart, bar for continuous time
Which categories are highest/lowest?	Sorted bar chart	Pie chart (hard to compare slices)
Do two variables move together?	Scatterplot	Dual-axis line chart (implies false causation)
What's the composition of a total?	Stacked bar, treemap	Pie chart with >5 slices
What's the exact value?	Table with conditional formatting	Charts requiring visual estimation
Where are exceptions?	KPI card with conditional color	Dense dashboards with no hierarchy
How is data distributed?	Histogram, box plot	Bar chart for distributions
What's the relationship across 2 dimensions?	Heatmap	Bubble charts (hard to compare area)