Merit grids rely on two variables: performance and pay position. Most HR teams spend significant time calibrating performance ratings. Far fewer examine whether pay position behaves consistently across different salary structures. The risk emerges when salary range spreads vary significantly across grades. This is not a behavioral bias problem. It is a structural design issue.
The Overlooked Design Risk
Salary ranges are not uniform across an organization.
Examples:
- Operational grades may have 40-50% spreads
- Technical or specialist grades may have 70-90% spreads
- Executive ranges are often even wider
If a merit grid applies identical compa-ratio bands across these uneven structures, it can introduce distortion - not because managers are biased, but because the underlying pay geometry differs.
The grid may be functioning correctly.
But it is operating on uneven foundations.
Why Spread Differences Matter
When range spreads differ:
- Employees in narrow ranges reach maximum pay faster
- Employees in wide ranges remain "mid-range" longer
- The same compa-ratio may represent very different career stages
- Progression speed becomes inconsistent across job families
Over time, this can lead to:
- Uneven compression risk
- Perceived inequity between technical and operational tracks
- Inconsistent long-term earnings growth
- Budget forecasting variability
The distortion is structural, not intentional.
Why Compa-Ratio Alone Can Be Insufficient
Compa-ratio compares pay to midpoint.
However, midpoint alignment does not account for total range width.
Two employees may share the same compa-ratio while sitting at very different structural positions within their respective ranges - particularly when spreads differ widely.
This makes cross-grade comparability less reliable.
The Role of Range Penetration
Range penetration measures where salary sits within the full span of its own range:
[ (Salary - Minimum) ÷ (Maximum - Minimum) ]
This expresses pay position as a percentage of total range progression.
Two employees at 50% penetration are equally positioned within their respective structures - regardless of whether one range is 40% wide and the other 80% wide.
Penetration normalizes progression logic.
Practical Illustration
| Grade | Range | Salary | Penetration |
|---|---|---|---|
| A | 60-90 | 75 | 50% |
| B | 100-180 | 140 | 50% |
Both employees sit halfway through their respective ranges.
If the merit grid uses penetration bands (e.g., 0-25%, 25-50%, 50-75%, 75%+), the system treats them consistently.
If the grid relies solely on compa-ratio, midpoint alignment may behave differently depending on spread width. One employee may appear appropriately positioned, while the other appears early in range - despite equivalent structural progression.
Range penetration removes that ambiguity.
Why This Improves Decision Integrity
Incorporating penetration into merit grids:
- Aligns progression with structural design
- Reduces hidden favoritism between job families
- Stabilizes long-term pay trajectories
- Improves cross-grade comparability
- Enhances defensibility in pay explanations
Most importantly, it reduces systemic error introduced by uneven spreads.
This matters in organizations where:
- Market-facing roles require wide competitive bands
- Operational roles use tighter structured ranges
- Executive ranges differ significantly from individual contributor ranges
- Multiple geographies apply different range philosophies
Without adjustment, identical grid logic can produce unequal progression behavior.
How to Communicate This Simply
The refinement does not need to be technical in employee conversations.
Framing can remain principle-based:
"Merit increases consider both performance and how far you have progressed within your role's pay range. Employees earlier in their range typically move faster, while increases moderate as pay approaches market competitiveness."
The mathematical normalization happens behind the scenes.
Key Insight
A merit grid sits on top of a pay architecture. If that architecture varies in spread, the grid must account for it.
Range penetration ensures that pay progression reflects true structural position - not accidental distortion created by uneven range widths. When the geometry is aligned, the grid functions as intended.