Field Note: Precision vs Accuracy
Date: 2025-01-08 Sector: FABRICATION Read Time: 4 minutes
In CNC machining, precision and accuracy are different things. Understanding this distinction changes how you diagnose problems, in manufacturing and everywhere else.
The Definitions
Precision is repeatability. Can you hit the same spot every time?
Accuracy is correctness. Is that spot the right spot?
You can be precise without being accurate (hitting the same wrong spot every time). You can be accurate without being precise (hitting near the right spot but inconsistently).
The Manufacturing Example
A CNC mill that consistently cuts 0.002" too deep has a precision problem and an accuracy problem. But they have different causes:
- Precision issues → mechanical wear, thermal expansion, vibration
- Accuracy issues → calibration, tool measurement, coordinate systems
Fixing vibration won't fix a calibration error. Recalibrating won't fix a worn bearing.
The Strategic Parallel
Organizations have the same distinction:
- Precise but inaccurate: Consistent processes that produce the wrong outcome
- Accurate but imprecise: Right goals, inconsistent execution
- Neither: Chaos
The Diagnostic Question
When something's not working, ask:
- Is it consistently wrong? (Precision is fine, accuracy is off)
- Is it inconsistently wrong? (Accuracy might be fine, precision is off)
- Is it randomly wrong? (Both are off, or you're measuring wrong)
The answer tells you where to look.
The Action
Before you start fixing, measure twice:
- Are you hitting the same spot? (Precision check)
- Is that spot where you intended? (Accuracy check)
Different problems. Different solutions.
This applies to: budgets, schedules, quality metrics, hiring, strategy execution, and anything else you measure.