Professional Detailing1 min read

Coating Sampling and Defect Detection: A Worked Probability Example

A sample can miss defects even when the inspected units are assessed correctly. A simple probability model helps explain why a small clean sample is limited evidence.

Updated · NANOLAB Knowledge

The key distinction

Under an illustrative independent-sampling model with a constant defect probability p, the chance of at least one defect in n observations is one minus (one minus p) raised to n. Real lots may require a different model.

Practical checks

  1. State the model assumptions.
  2. Use the calculation to understand detection, not to invent a release rule.
  3. Obtain a sampling plan appropriate to the actual lot and decision.

Example

Arithmetic example: with an assumed ten-percent defect probability and ten independent observations, detection probability is about 65.1 percent. Missing all defects still has about a 34.9 percent probability in that model.

Scope and limits

These assumptions are hypothetical, not NANOLAB quality data. Dependence, finite lots and imperfect inspection can change the calculation and require qualified analysis.

Related guidance

Ask NANOLAB about the exact product and intended use. Use the current product documentation for formulation-specific instructions.