I think I have actually cracked it, many thanks for all the input, it is really useful to bounce things around.
If I make:
1. A table of all unique serial numbers
2. A table of all that failed in the last instance
3. A table of all that passed in the last instance
I will then have my list of failures and by subtracting the passes and then the fails from the complete list will also have the list of uncertainties.
If I make:
1. A table of all unique serial numbers
2. A table of all that failed in the last instance
3. A table of all that passed in the last instance
I will then have my list of failures and by subtracting the passes and then the fails from the complete list will also have the list of uncertainties.