(a) Alternative sampling plans must meet FTA’s 95% confidence and 10% precision levels.
(b) In addition to these basic statistical requirements, alternative sampling plans should also meet the following requirements:
(1) They are based on the conditions of your service. That means that they should be developed with sample data collected from a random sample of your service.
(2) The sample data used for developing alternative sampling plans have a minimum sample size of 50 service units.
(3) They contain a margin of safety of at least 25%. That is, the final sample size of an alternative sampling plan is at least 25% greater than what you would get from using the sample data directly.
(4) The final sample size of any alternative sampling plan is at least 50.
(c) Template sampling plans also should meet the additional requirements in (b) as specified in Section 50.