The 'C4S Rule'
This is a procedure to achieve a post-error analysis with a minimum of effort and costs.
The ‘C4S Rule’:
The “C4S” stands for collect four samples: Collect one sample each week and put it in the freezer. Discard the sample collected four weeks ago. This ensures that there are always four samples available, which have “stored” the digester state of the last four weeks .
Fig.: Scheme of the 'C4S Rule'.
In case of an incident analysing all samples discloses important information about the steps which lead to the the incident:
- The oldest sample holds the state BEFORE the incident started (target state).
- The joungest sample describes the current state.
- Both samples in between provide clues about when the aberration started and what the root cause may have been.
Advantages:
- Costs occur only when a problem happens.
- Monitoring the development of the incident in time allows a fact-based error analysis.