Inspection Sampling Process
How We Select Samples — AQL-Based Random Sampling
All product inspections at QCINASIA follow the ANSI/ASQ Z1.4 (ISO 2859-1) Single Sampling Plan under Normal Inspection Level II, unless otherwise instructed by the client.
1. Determine the Sample Size
- Identify the lot size (total quantity in the shipment).
- Cross-reference against the AQL table to determine the required sample size (n) based on your agreed AQL levels (typically Critical = 0 / Major = 2.5 / Minor = 4.0, or as customized per client spec).
2. Carton Selection — "Square Root Rule" (Randomized, Not Convenient)
At minimum, we randomly open √N cartons (where N = total number of cartons in the shipment), or a higher quantity if defined by the client's SOP.
⚠️ Key principle: Cartons must be selected from all positions of the pallet/stack — front & back, top & bottom, left & right, and interior — never only from the accessible outer layer.
❌ Don't | ✅ Do |
| Take all cartons from the easiest front-facing row | Systematically pick from different depths and sides of the pallet |
| Assume outer cartons represent the whole lot | Ensure random distribution across the entire shipment |
3. Proportional Sampling from Inside the Cartons
Samples are drawn proportionally from the opened cartons. If the currently opened cartons cannot yield enough samples to meet the AQL sample size, we continue opening additional cartons until the required quantity is fulfilled.
Within each opened carton, pieces are randomly picked from different layers, different polybags, or different positions — not just the top-facing items — to maximize representation of the true production quality.
4. When Goods Are Not 100% Packed (Mixed Packed / Unpacked Status)
If part of the lot is still in bulk (unpacked) at inspection time, we sample proportionally between packed cartons and loose pieces.
Example:
- Lot = 5,000 pcs
- Packed in cartons = 4,000 pcs → sample 160 pcs from cartons
- Unpacked / loose = 1,000 pcs → sample 40 pcs from loose stock
- Total AQL sample size = 200 pcs
Ratio: 4,000 ÷ 5,000 = 80% from cartons / 1,000 ÷ 5,000 = 20% from loose
This ensures the sample reflects the actual mix the buyer will receive, not just the "already boxed" portion.
A proper sampling process isn't about "opening a few boxes and eyeballing." It's about ensuring the statistical confidence behind every release decision — protecting both the buyer's brand and the factory's reputation.
QCINASIA's field teams are trained to sample randomly, thoroughly, and defensibly — so your inspection report stands up to audit, claim, and real-world performance alike.