The choice of sample size starts in Risk Management. You need to determine what defect rates are allowed based on classifying the defect types. More critical defects that cause serious harm to the user require better quality. Acceptable rates may vary from 0.1% for very serious defects up to 6-10% for cosmetic issues. You also must choose a confidence level for your final conclusions. 90% or 95% are common values. Once those two values are determined, calculating a sample size is just a math problem. Remember, you will have to justify the acceptable defect rate to outside auditors.
GLOBAL BOTTOM CTA INSTRUCTIONS:
To display custom copy instead of global copy in this section, please go to Show Global Content for Bottom CTA? toggle in the "Contents" tab to the left, toggle it off, save, and then REFRESH the page editor, the custom text will then show up and ready to be edited.
Turning the global content back on will be the same process, go to the toggle and toggle it back on, save and refresh!