Probesetzpläne

Probesetzpläne, often translated as "sampling plans" or "inspection plans," are systematic procedures used in quality control and statistical process control to determine the number of items to be inspected from a batch or lot and the criteria for accepting or rejecting that batch. These plans are designed to balance the risk of accepting defective items with the cost of inspection.

The core principle behind probesetzpläne is statistical inference. Instead of inspecting every single item in a production run, which can be time-consuming and expensive, a representative sample is taken. The quality of this sample is then assessed, and based on the results, a decision is made about the entire lot. If the sample meets predefined quality standards, the lot is accepted. If it falls below these standards, the lot may be rejected, requiring further inspection or corrective action.

Various types of probesetzpläne exist, each suited for different situations. Single sampling plans involve taking one sample from a lot. Double sampling plans allow for a second sample to be taken if the results of the first sample are inconclusive. Multiple sampling plans extend this concept to several sequential samples. Acceptance sampling plans are a broad category encompassing these variations, with specific plans often defined by standards organizations like ISO or ANSI.

The design of a probesetzpläne typically considers factors such as the acceptable quality level (AQL), the lot size, the desired level of confidence, and the producer's and consumer's risks. The producer's risk is the probability of rejecting a good lot, while the consumer's risk is the probability of accepting a bad lot. Effective probesetzpläne aim to minimize these risks while ensuring efficient quality assurance.