Our proposed standard of quality is as Wally indicated. 85 percent of batch coverage of the 75 to 125 percent label claim target interval should be covered and this corresponds to the 5 percent acceptance point for the FDA multi-dose product test. Importantly, this means that commercial batches must far exceed the 85 percent coverage; otherwise the reject rate would be unacceptably high.
So here's a comparison between the coverage at the limiting quality between the FDA and the PTI tests. So the PTI proposal is the same coverage as with the FDA test for multi-dose products and exceeds that for single-dose products.
This is a summary of the actual mechanics of the PTI test. You test a predefined number of units and those are from different portions in the container life, if it's a multi-dose product, one dose from each unit. From this sample, one calculates the mean and the standard deviation, and this is what makes this test a parametric test because these are the parameters of a normal distribution.
From these parameters, an acceptance value is