Baseline Acceptable Quality Limit Qualification Matrix Setup
A clear AQL matrix binds defect classification to statistical sampling tables, shifting commercial re-inspection costs to factories on lot failures.
Sample Size Code Letter
Meaning
Indexed symbols facilitate the transition between a total batch quantity and the required amount of testing in a quality control plan. The sample size code letter is found by matching the lot size to one of the general or special inspection levels in a standard table. This letter then points the inspector to the exact number of units that must be drawn from the production run.
It ensures that the sampling intensity is proportional to the scale of the manufacturing output.
Index Logic
Alphabetic identifiers simplify the communication of sampling requirements between factories and external auditors. Each sample size code letter represents a specific tier of inspection effort determined by the risk profile of the goods. A letter appearing late in the alphabet generally signifies a larger number of units for the test.
Quantity Correspondence
Tables within the GB/T 2828.1 standard link each character to a specific numeric value for the sample. Once the sample size code letter is determined, the inspector no longer needs to refer to the original lot size. This separation of the lot size from the sample quantity allows for consistent application across different product categories.
Smaller batches might use a letter like A or B, while massive shipments move toward the end of the alphabet. An inspector who identifies a letter K for a batch of five thousand units will find a requirement for two hundred samples.
Batch Scale
Voluminous production requires a higher level of scrutiny to maintain statistical confidence in the quality of the goods. The sample size code letter adjusts the burden of inspection so that it remains manageable while still being statistically representative. This prevents the under-sampling of large shipments which would hide systemic defects.