Scenario
You've been assigned to lead a Six Sigma project aimed at "reducing customer complaints." In the first week, you interviewed 10 customers, and each said something different: some complained about long delivery times, others about fragile packaging, large dimensional deviations, and some about poor communication.
Do all of these need to be solved? Or should you choose?
What is VOC
VOC (Voice of Customer)
Customer's needs, expectations, complaints, and opinions about products or services.
Collection Methods:
- Customer complaint records: Direct data from failures, most important
- Customer interviews: In-depth understanding of underlying needs, but requires the right questioning techniques
- Surveys: Quantify priorities
- Field observation: See how customers actually use your product
- Competitor comparison: Why customers buy competing products
Pitfalls of VOC:
What customers say is not necessarily what they truly want. "I want a faster horse" actually implies "I need faster transportation." Interviews should ask "why" to uncover the underlying true needs.
What is VOB
VOB (Voice of Business)
The enterprise's own strategic goals, financial requirements, regulatory constraints, and resource limitations.
Sources:
- Financial goals (cost, profit, revenue)
- Strategic direction (new markets, new products)
- Regulatory requirements (ISO, customer audits)
- Internal limitations (budget, human resources, equipment)
Importance of VOB:
What customers want is not necessarily what the company can or should do. VOB helps you filter VOC—identifying which customer needs align with company strategy and which are beyond its capabilities.
VOC → CTQ Transformation
Having VOC alone is not enough; vague needs must be transformed into measurable CTQs (Critical to Quality).
Transformation Steps (KJ Method + Affinity Diagram):
- Collect all raw VOC statements
- Organize and categorize (Affinity Diagram): Group similar needs together
- Define quality requirements: What is the core need for each category
- Transform into CTQ: Specific, measurable quality characteristics
Example:
| VOC Original Statement | Quality Requirement | CTQ |
|---|---|---|
| "The product often breaks" | Reliability | MTBF ≥ 2000 hours |
| "Delivery is always delayed" | On-time delivery | On-time delivery rate ≥ 98% |
| "Dimensions are inconsistent" | Dimensional accuracy | Critical dimension Cpk ≥ 1.33 |
Handling Conflicts between VOC and VOB
| Conflict Situation | Handling Method |
|---|---|
| Customer requirements exceed cost limits | Evaluate price increase or compensate by reducing other costs |
| Customer requirements conflict with regulations | Regulations take precedence; explain to the customer |
| Conflicting needs among different customers | Prioritize by customer importance, find the common ground |
| VOC and VOB directions differ | Submit to management for decision, not to be decided by engineers alone |
Golden Quote
"Starting process improvement without knowing what the customer wants is like setting off without a destination—you might be moving fast, but in the completely wrong direction."