Most Invalidated OOS with laboratory error as root cause may fall into Inconclusive OOS.

• For example, in a chromatographic sequence for assay with several samples only one or two samples fails in assay. If this OOS is invalidated with probable root cause of laboratory error like air bubble or analyst error in sample preparation, the root cause is Inconclusive. The question is why only specific samples are OOS in the same sequence when other samples comply.
• ·On the other hand, an OOS with laboratory error where column performance has deteriorated giving poor peak shape, may still pass muster as Conclusive laboratory error.
• The former requires manufacturing investigation while latter may not 

USFDA OOS Guidance, MHRA OOS Guidance