Hierarchical models, or multilevel models, are used to represent data that might vary on, you guessed, different levels. Michael Freeman, from the University of Washington Information School, provides an introduction to the method using a scrolling format. The transitions give a good sense of how the model can change, depending on your approach.
Visual explainer for hierarchical modeling
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Unemployment in America, Mapped Over Time
Watch the regional changes across the country from 1990 to 2016.
3-D-Printed Time Series Plates
After seeing a 1950s physical visualization, I wondered if I could follow a similar process using modern techniques.
Days Without a Mass Shooting
Unfortunately, while of varying magnitude, mass shootings are somewhat regular in the United States.