Understanding Heat Maps
In this lesson, we’re exploring heat maps - a visualization that uses color intensity or patterns to show relationships between two categorical variables.
A heat map is like a grid or table where:
- Rows represent one category
- Columns represent another category
- Each cell shows a value through color intensity or pattern
- Higher values typically have stronger intensity
- Lower values typically have lighter intensity
Think of it like a temperature grid of a room, where each square represents how warm or cool that spot is.
Structure of a Heat Map
- Grid Layout:
- Rows and columns form a matrix
- Each cell represents an intersection
- Labels on both axes identify categories
- Values Representation:
- Numerical values in each cell
- Color intensity shows magnitude
- Patterns can replace colors for accessibility
Example: Weekly Activity Schedule
Let’s explore a student’s weekly activity levels across different times:
- Days (Rows):
- Monday through Friday
- Time Slots (Columns):
- Morning (8-12)
- Afternoon (12-4)
- Evening (4-8)
- Activity Levels (Cell Values):
- High: 8-10 hours (intense)
- Medium: 4-7 hours (moderate)
- Low: 0-3 hours (light)
Common Applications
- Time-Based Patterns:
- Weekly schedules
- Monthly activities
- Seasonal variations
- Correlation Matrices:
- Relationship strength between variables
- Pattern identification
- Cluster analysis
- Geographic Data:
- Population density
- Weather patterns
- Economic indicators
Common Patterns to Listen For
- Clusters:
- Groups of similar values
- Hot spots (high values)
- Cold spots (low values)
- Gradients:
- Smooth transitions
- Value progression
- Directional changes
- Outliers:
- Unexpected high values
- Unexpected low values
- Irregular patterns
Reflection and Exploration
Think about data that could be shown in a heat map:
- Your daily schedule
- Monthly expenses by category
- Activity levels throughout the day
Up Next
In the next lesson, you’ll learn about another data visualization, the scatter plot, which is used to show the relationship between two numerical variables.