A slopegraph is a type of line chart that compares changes in values between exactly two time periods or conditions. Each line connects a category's starting value (left) to its ending value (right). The slope of each line immediately shows whether values increased or decreased, and by how much.

Popularized by Edward Tufte, slopegraphs are ideal for showing ranked comparisons, before-and-after data, and changes across two conditions.

• Comparing rankings between two time periods
• Before-and-after studies or experiments
• Showing how multiple categories changed simultaneously
• Highlighting which items increased vs decreased
• Comparing survey results across two groups
• Economic data across two years (GDP, population, etc.)

• Keep the number of categories manageable (under 15-20 is ideal)
• Use clear, descriptive labels for both time periods
• Consider using directional coloring to highlight increases vs decreases
• Show values alongside category names for precision
• Order categories by starting or ending value for easier reading