Dual-Axis Classification
The Principle
When modeling complex domains, using two orthogonal axes creates four quadrants that naturally organize different types of information, each with distinct purposes and maintenance characteristics.
Why This Matters
Single-axis taxonomies force false choices. Hierarchies that organize by only one dimension (e.g., by department, or by topic) create friction when users need to access information along the other dimension.
Two orthogonal axes (chosen well, create a matrix where each quadrant serves a distinct purpose. The O*NET Content Model uses:
- Worker-oriented ↔ Job-oriented
- Cross-occupational ↔ Occupation-specific
This creates four quadrants with different characteristics:
Cross-occupational + Worker-oriented: Universal human attributes (abilities, interests). Changes slowly. Enables person-to-person comparison.
Cross-occupational + Job-oriented: Universal work activities. Changes moderately. Enables job-to-job comparison.
Occupation-specific + Worker-oriented: Entry requirements. Changes with market conditions. Enables qualification assessment.
Occupation-specific + Job-oriented: Unique tasks and skills. Changes with technology and practice. Enables deep job understanding.
How to Apply
- Identify two dimensions that are genuinely orthogonal (not just variations of the same thing)
- Ensure both dimensions are meaningful to users (not just theoretically elegant)
- Confirm that each quadrant represents a coherent category with consistent maintenance needs
- Design different update cycles for each quadrant based on its rate of change
When This Especially Matters
Any domain where:
- Users need both comparison and depth
- Information changes at different rates in different areas
- Multiple stakeholder groups need different views of the same underlying reality
Related: 06-molecule—onet-content-model-framework, 02-molecule—faceted-classification