Normal Inspection
Meaning ~ Normal inspection defines the default statistical sampling plan used to accept or reject production lots based on stable history and standard risk levels.
Oc Curve
Meaning
Graphical representations that show the probability of accepting a lot for different levels of incoming quality. The oc curve visualizes the risks shared between the producer and the consumer. It maps the performance of a specific sampling plan across a range of potential defect rates.
Probability Visualization
The vertical axis of the graph represents the chance of acceptance while the horizontal axis shows the percentage of non-conforming items. A steep oc curve indicates a plan that is effective at distinguishing between good and bad lots. This visual tool helps quality managers select the right sample size for their needs.
Risk Allocation
Every sampling plan carries the danger of rejecting a good lot or accepting a bad one. The oc curve identifies the producer risk and the consumer risk at specific points. Adjusting the acceptance number changes the shape of the graph and shifts these risks between the parties.
Sample Performance
A plan with a larger sample size produces a curve that is closer to the ideal vertical line. While this increases the cost of inspection, the oc curve demonstrates the resulting improvement in protection. Engineers use these graphs to justify the time spent on testing to the senior management of the company.
A clear visualization of the data makes it easier to communicate the limitations of the quality control process.