The Role Of Acceptance Sampling

By Marcia Marks


Acceptance sampling is a statistical method used for quality control of production lots. The material in the package can be either accepted or denied. A sample is collected from the whole production line, which is examined and if it passes the test, the whole goes forward as well. Every piece cannot be verified, because it would consume too much time.

The procedure is usually performed when a product is still inside the production facility, or it leaves the factory. The first application of the method was made in the World War II, by the US military. The purpose of the operation was to test bullets, because the use of malfunctioning pieces could have a disastrous effect. A random sample was about to be picked from the production line and verified.

The level of acceptance can be determined by the amount of defects that could exist and quality is not the top priority. The most important thing can be deciding if a lot will be released on the market or not. A large stock is handed to the consumer, but only when the amount of defects does not cross the established limits. A total assurance cannot be offered, because just a sample is usually collected in a certain production line.

There are three modes of applying the method: single, double, or sequential. The first way involves a limited amount of samples and a specific number of defects to establish. The second type can have more variables involved, but it is still not very different from the single one. Sequential is a variant of the primary type that has some extensions.

One of the reasons for which the procedure is helpful in many industries is that you do not have to destroy or consume entire batches of products for testing purposes. The way the testing works can be explained through examples from real production. A company may want to verify if no more than ten percent of its production of candies is broken. Five percent of the current lot is tested and if there are more broken candies than the established limit, the whole lot will be refused.

The firm is the one that establishes the acceptable defect percentage and the numbers can vary. Another important decision is related to choosing the samples for testing. Statistical procedures are normally used. Every company needs to select the size of the batch that is a representation of the corresponding larger lot.

In most cases, the sample used for a test is representative for the batch and is also considered quality verification. The higher the percentage is, the poorer a lot can be. For batches that required high standard, the percentage is kept at the lowest level.

The use of acceptance sampling is a regular practice for companies in different industries. Depending on the quality of the production lot that is needed, there are various maximum percentage levels used. There are specific examples that can show people how the method works and why it is useful for companies.




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