Analytical quality
How to Compare Results Between Batches
Comparing batches: Does the batch difference exceed differences introduced by the method?
Source editorial review:
Before interpreting the result
Does the batch difference exceed differences introduced by the method?
- Match SKU, batch, presentation, sample and document date.
- Compare units, preparation, method and acceptance criterion.
- Keep uncertainty and changes in laboratory or method version visible.
Comparing batches
Batch comparisons require separating material variation from procedural variation. Documents with different methods, calculation bases or histories may not support direct comparison. Batch identifiers connect samples with records, but interpretation also requires knowing how each was prepared, measured and reported.
A reading case: what to check
If two certificates show different percentages, first check whether they describe the same quantity using comparable methods. When investigating an experimental change, also record laboratory storage and preparation. Do not use an isolated difference to assign causality. A documented comparison can identify a hypothesis worth investigating without resolving it yet.
What to preserve in the record
Two percentages do not make a complete comparison. If the measurement basis changed, describe that difference before attributing the result to manufacturing.
Questions and answers
Does the batch difference exceed differences introduced by the method?
Batch comparisons require separating material variation from procedural variation. Documents with different methods, calculation bases or histories may not support direct comparison. Batch identifiers connect samples with records, but interpretation also requires knowing how each was prepared, measured and reported.
What should the review record preserve?
Two percentages do not make a complete comparison. If the measurement basis changed, describe that difference before attributing the result to manufacturing.