This stage tests the assumptions made in relation to the controls and their level of effectiveness, and also implements the monitoring arrangements determined in stage 3.
Using a risk based prioritisation, the higher level controls should be audited to ensure that they are in place. It is for the assurer/inspector to determine the degree of sampling and number of controls reviewed. In the manual handling example from stage 3, the number of checks made on the quality of manual handling training may need to be monitored to ensure that manual handling techniques are being properly understood by those involved in handling ramps.
RSSB has produced guidance on determining the type of monitoring needed in an organisation and who should monitor performance. This document provides guidance on how to select the right types of health performance indicators, using the bow tie as the key reference document.
While performance measures are being developed and implemented, it may be appropriate to use audit as a one off check that controls are in place. Doing this would mean that the bow tie can then be updated to reflect the actual state of controls, as opposed to the theoretical/assumed status.
Figure 1 below provides an overview of a six stage approach to assurance. The last three stages form a management cycle once the first six steps are completed.