A variable sampling plan based on the coefficient of variation for lots resubmission.

Area of Science:

• Industrial Engineering
• Quality Control
• Statistical Process Control

Background:

• Lot resubmission is a significant issue in quality inspection processes, often stemming from initial inspections resulting in held or rejected lots.
• Existing inspection methods can be inefficient, leading to unnecessary delays and increased costs associated with lot resubmission.

Purpose of the Study:

• To develop and evaluate a novel variables sampling plan for lot inspection.
• To minimize the average sample number while adhering to specified operating characteristic curve criteria.
• To provide practical guidance for implementing the proposed sampling plan in industrial settings.

Main Methods:

• A new variables sampling plan was designed, utilizing the coefficient of variation as the key statistical measure.
• Sampling plan parameters were optimized to minimize the average sample number (ASN).
• Operating characteristic (OC) curve properties were used to define acceptance criteria, ensuring both producer's and consumer's risks were managed.

Main Results:

• The proposed sampling plan demonstrates efficiency in reducing the average sample number compared to traditional single sampling plans.
• Tabulated values for inspection sample size and acceptance criteria are provided for various quality levels and risk parameters.
• Comparative analysis confirmed the advantages of the coefficient of variation-based plan over existing single sampling plans.

Conclusions:

• The novel variables sampling plan based on the coefficient of variation offers an effective solution for managing lot resubmission in inspection processes.
• The plan provides a statistically sound and practically applicable method for optimizing sample size and ensuring product quality.
• Implementation guidance and comparative data support the adoption of this advanced sampling strategy in quality control.