Data Visualization Explained (Part 2): An Introduction to Visual Variables

Visual encoding channels are the fundamental concept for representing data visually by translating it into marks with attributes like position, size, and color. The effectiveness of these visual variables depends on the data type being represented, whether it is quantitative, ordinal, or nominal. Position is considered the most effective encoding for all data types, while others like color hue are better for nominal data. Charles Minard's famous map of Napoleon's invasion of Russia is a masterful example, using multiple variables like position, width, and color to convey six different types of information. Understanding these principles is key to designing clear and impactful data visualizations.