In a strict standard grading system, each attribute of a product is evaluated independently, according to defined characteristics, and assigned a grade:
- A (Excellent)
- B (Acceptable)
- C (Poor)
Moreover, tolerance is applied per attribute, allowing a limited percentage of out-of-limits results before affecting the attribute’s final grade.
Key Rules:
- The final inspection grade is determined by its lowest result.
- If tolerance is applied the lowest result that is not ignored determines the final grade.
- If 20% tolerance is allowed and 5 inspections are conducted, then 1 ‘C’ rating can be ignored when determining the attribute’s final grade.
- If more than the allowed number of ‘C’ ratings occur, the attribute's grade is 'C'.
Example: Apple Inspection with Attribute-Specific Tolerance
An inspector evaluates apples based on the following attributes:
- Brix (Sweetness)
- Color
- Size
- Appearance
- Acidity
Each attribute has 5 inspections, and 20% tolerance (1 low result is ignored per attribute).
Scenario 1: No Attribute Exceeds Tolerance
| Attribute | Inspection Results | Allowed Tolerance | Ignored result | Attribute Grade |
|---|---|---|---|---|
| Brix | A, B, B, B, C | 20% (1 allowed) | C | B |
| Color | A, A, B, B, C | 20% (1 allowed) | C | B |
| Size | A, A, A, A, B | 20% (1 allowed) | B | A |
| Appearance | A, A, B, B, C | 20% (1 allowed) | C | B |
| Acidity | A, A, A, A, A | 20% (1 allowed) | A | A |
✅ Final Product Grade: B (Lowest attribute grade is B)
Why?
Since the worst grade after applying tolerance is ‘B’, the final grade is B.
Scenario 2: An Attribute Exceeds Tolerance
| Attribute | Inspection Results | Allowed Tolerance | Ignored result | Attribute Grade |
|---|---|---|---|---|
| Brix | A, B, B, C, C | 20% (1 allowed) | C | C |
| Color | A, A, B, B, C | 20% (1 allowed) | C | B |
| Size | A, A, A, B, A | 20% (1 allowed) | B | A |
| Appearance | A, A, B, C, C | 20% (1 allowed) | C | C |
| Acidity | A, A, A, A, A | 20% (1 allowed) | A | A |
❌ Final Product Grade: C (Lowest attribute grade is C)
Why?
- Brix and Appearance had 2 ‘C’ ratings each, which exceeds the allowed 1 ‘C’ tolerance.
- These attributes are downgraded to C.
- Since the lowest attribute grade is C, the final product grade is C.
Key Takeaways
- Each attribute is graded separately. Tolerance can be applied at the attribute level.
- Set tolerance 0-100% to prevent one/a few out-of-limit results from lowering the grade.
- If an attribute exceeds tolerance (too many out-of-limits results), its grade is downgraded.
- The final product grade is based on the lowest attribute grade.