Statistical sampling is required for design verification and validations. If you have worked for a company or written protocols in the past – how have you explained or ensured that the sampling plan and statistical approach you have taken has been sufficient?

For myself, I have written validation protocols in the past and usually it depends on the extent of the validation if it is minor or critical or variable or attribute data we are measuring. From there we look at 90% reliability and 90% confidence (example) and determine how many samples we need based on that. The acceptance criteria for the test comes afterward along with the statistical analysis. This is a very basic and high level approach. I’m curious as to how people approach the reasoning and explanation behind the amount of samples they choose for verification and validation.