It’s not very often you see a bowtie that can be understood by a knowledgeable outsider.
The most common problems centre around inconsistency of context: bowties should occupy a specific position along the four axes which define the context: discipline, detail, time and location. Unless these dimensions are agreed and understood by all participants in a bowtie workshop, it is unlikely the results will stand up to later scrutiny.
The discipline axis constrains the scope of the subject matter brought to bear on the bowtie, ensuring that the language and conventions used are uniform.
The detail axis constrains the degree of depth gone into, ensuring that all elements are at or around the same level of detail.
The time axis constrains the sequential nature of the bowtie, ensuing that, wherever possible, the flow from the fault tree (the left hand side) into the event tree (on the right hand side) is layered and each layer has some dependence on the preceding layer.
The location axis constrains the spatial interactions inherent in the elements of the bowtie, ensuring that the map of dependence between the -elements maintains a presence with the preceding and succeeding layers.
Of course these are broad generalisations and so invalid on all counts, but they orient what comes next, and can hopefully be excused.
First of all, a bowtie must be a map of the risk. And to be an effective map, like any, it must be useful in navigating unfamiliar territory for someone trained in map reading. Gathering the details for bowties relies on a subtle blend of skills, the foremost of which is flexibility, but a clear sense of direction and approach will lay the groundwork for a consistent, utilitarian and beneficial outcome.
Rule 1 – Know where each bowtie fits in the overall risk context of your business.
So many bowties overlap with each other, repeating elements, increasing inconsistency and making maintenance difficult. And no one wants to re-do work they or someone else has already done. Start with a 40,000 ft map of your risks and then drop down to the next level to partition those risks into similar sized, interconnected chunks that define in a consistent manner, the “borders” for each risk. Once validated, that high-level map provides a clear check-list for the process.
Rule 2 – Ensure that your workshop is filled with people who best know the terrain in question.
Multi-disciplinary teams provide the best input to bowties but you need overlapping expertise to ensure everyone’s position is validated, a kind of triangulation if you will.
Rule 3 – Ensure that each bowtie remains roughly within its borders and that the detail for each is consistent.
Publish the high-level map prior to the workshop so that everyone arrives ready for a series of specific tasks, not a treasure hunt. Quickly rule suggestions in or out of scope and record them for later follow-up.
Rule 4 – Ensure that you have a range of examples to cover repeating decision points and that these are provided in advance. Everyone normally gets a copy of the risk matrix and the background numbers but often the terms or numbers used are hard to relate consistently to shared real-world experiences. Providing examples of actual likelihood frequencies and severities prior to the workshop and then validating the understanding as a first order of business cuts down on repetitive and demoralising debates.
Rule 5 – Ensure that definitions and examples of Causes, Controls and Consequences are provided in advance.
It will surprise no one that the three Cs are often confused and that much time can be lost pursuing controls for a cause that is really a failed control and therefore shouldn’t have been there in any case. Specify the terminology to be used in all categories and for controls, it is often useful to break them down into an agreed set of controls that are typical: hard/engineering or soft/admin/system, etc. Defining at which layer a control exists can sometimes be helpful as it suggest prior and succeeding controls. Also, sometimes, it may be useful to agree that cultural controls, like high level corporate communications be excluded from the bowtie as they can provide too much clutter.
Rule 6 – The Top Event should always reflect the point at which control over the scenario is lost.
Some companies will want all their controls to be preventative and none to be mitigative, because the consequences of any loss of control could be catastrophic. Toyota, it is said, knows that recalls cost billions so they want to do everything they can before a vehicle leaves the factory. Other companies don’t. Also, it can be good practice to use Intermediate Events aid to clarify potential failure modes and their probabilities.
Rule 7 – Every element on a bowtie must earn a right to be there.
Clutter can make bowties unreadable and therefore useless, so ensure that every element gets a stern test before being allowed on. There is one except to this rule: recording of rejected elements, i.e. an element which has been considered but then found to be not plausible (in the case of a cause), or not a valid control, etc. Sometimes, it is more convenient to leave them on, and marked as rejected, as they save future review workshops from debating it, but also if conditions change, then so can the status of those items.
Rule 8 – Controls, like People, don’t live in isolation.
Consider what processes verify a control’s presence and performance and what would happen were an assumption about either factor be mistaken. There are layers of controls in place and if material to the bowtie’s context, they need to made explicit. Also, careful not to overuse Escalation Factors as they should normally occupy a place in the Control’s Performance Standard, and therefore remove a little more clutter from the bowtie.
Rule 9 – Challenge all assumptions in the workshop, not later.
The best time to get things finalised is in the workshop while everyone is together and on-topic. Working through larger bowties can take sometime, but a final review on a causal pathway by causal pathway basis ensures oversights are caught and eradicated.
Rule 10 – Document all assumptions.
Recording the basis for all decisions ensures that the bowtie can easily be revalidated in the future. If no one can find out why a particular decision was taken to reject a control, then they have to go through all the thinking again next time.
There are many more, and even then, reasons to break most of them.
Bowties are a collaborative work and subject to bias but in the right hands they scale the heights, representing the best of collective wisdom.