A spike map is a type of data visualization used on geographic maps to represent quantitative data using 3D "spikes."
According to the reference provided, spikes of (usually) equal width but varying height are centered on geographic areas. These spikes rise vertically from the map, with the height of each spike corresponding to the value of the data at that location.
How Spike Maps Work
Spike maps visually emphasize differences in data values across different locations. The taller the spike, the higher the value it represents in that specific geographic area.
Key Characteristics:
- Geographic Basis: Data is tied to specific locations on a map.
- 3D Representation: Uses vertical spikes to show magnitude.
- Varying Height: Spike height corresponds to the data value (e.g., population count, sales figure, crime rate).
- Equal Width: Spikes typically have the same width for consistency.
Common Uses
Spike maps are particularly effective at highlighting areas with unusually high concentrations or counts of a phenomenon.
- Showing Hotspots: They are often used to show abnormally high counts in concentered regions. This makes them useful for identifying areas that require particular attention or analysis.
- Population Density: Visualizing population clusters in urban areas.
- Sales Performance: Showing regions with exceptionally high sales figures.
- Crime Analysis: Identifying areas with high crime rates.
- Disease Outbreaks: Mapping locations with a high number of cases.
Examples
Imagine a map showing population density. A spike map could represent this where:
- Tall spikes indicate densely populated cities.
- Shorter spikes show less populated areas.
Similarly, mapping retail sales using spikes would quickly reveal the top-performing store locations or sales territories.
Advantages and Considerations
Spike maps offer a dramatic visual representation that can immediately draw attention to key areas. However, they can sometimes obscure underlying map details or neighboring spikes if the data range is very large and spikes are too tall or dense. Effective spike maps require careful design, including choosing the right scale for spike height and appropriate mapping projection.
