We use probability (likelihood) as a measure of how likely we believe it is that an (undesired) event will occur, based on the knowledge we have available. At the University of Bergen, the probability is expressed in terms of frequency (how often the event might occur). Show Probability can be estimated using the criteria for probability. These criteria can be used for both Risk and Vulnerability Analyses (RVA-analysis) and HSE risk assessments. Probability Frequency 1 Highly improbable Occurs less often than every 10 years. 2 Improbable Between once every 5 years and once every 10 years. 3 Probable Between once every year and once every 5 years. 4 Very probable Between once a month and once a year. 5 Highly probable Once a month or more often. Sometimes, the probability criteria we use at the University of Bergen will not be the right fit for your risk assessment. The range of frequency may be too extensive, e.g., for events that occur relatively frequently, or too limited for events that occur very rarely. This will impact how the event is plotted in the risk matrix, and may illustrate risk that is unrealistically high or low. This should be noted in the report for the risk assessment. It is also possible to omit the estimation of probability, but you must always provide reasons for this in the report. Estimate probability using the criteria to the best of your ability, it is not expected that you will be able to see into the future. We recommend using former experience of the same or similar events, and discussing these in groups to discover what aspects are deemed probable. Consequence assessmentConsequences are the possible outcome of an undesired event, and may involve loss of or damage to values we want to protect. Consequence is estimated by first imagining the outcomes of an undesired event. One event can have several different consequences. We assess consequence in relation to our different values:
The categories of consequences for each value are as follows:
The criteria for consequence provide a definition of these categories of consequences in relation to our values. Worst possible consequence An undesired event may have several different consequences of varying severity, and it is easy to think of the worst possible outcome of events when carrying out a risk assessment. It is important to remember, in this regard, that the probability of the worst possible outcome will often be lower. It is therefore important to adapt probability to the outcome. This does not mean that it is wrong to envisage the worst possible outcome, and it can often be appropriate to show that an activity may have very serious consequences. We may also come across examples of undesired events that are both very probable and could have severe consequences. In such a case, it is important to introduce risk-reducing measures as quickly as possible. As a main rule, the probability of the worst possible outcome is low, and other outcomes are more probable. Nonetheless, the worst possible outcome can be emphasised if deemed appropriate. You do so by dividing the event into parts and assessing the individual levels of severity, with their associated probability. The example below is hypothetical. It is important to reach your own decisions when carrying out a risk analysis of a similar problem: Example Undesired event Consequences Probability Consequence 1 An employee is injured while transporting material in and out of a campus building. Acute strain injury Injuries from wear an tear Crush injury Minor injury caused by fall “Very probable” Between once a month and once a year. “A certain hazard” Few or minor physical or psychological injuries. 2 An employee is severely injured or dies while transporting material in and out of a campus building. Severe injury caused by fall Death “Not very probable” Occurs less often than every 10 years. “Very critical” Death. There are so many things that would have to go wrong for the terrible outcome in example 2 to occur, so the estimate of probability is different for this outcome. The consequences in Example 1 are more probable and the probability is adapted accordingly. What is the likelihood of the risk?Risk Likelihood is the state of being probable or chance of a threat occurring.
What is the difference between likelihood and impact in risk management?The impact is an estimate of the harm that could be caused by an event. For example, a cyberbreach could have a catastrophic impact. Likelihood. Likelihood is how probable it is that an event will occur.
What is likelihood and magnitude of risk?Likelihood Magnitudes
The likelihood of occurrence of each Undesired Outcome can be thought of as the bridge between the Severity and the Risk. An outcome with a given severity will have a greater risk if it is more likely to occur, and a lesser risk if it is less likely to occur.
What is the difference between likelihood and severity?Low severity risks can be a minor inconvenience while high severity risks could bring irreversible damage or collapse an organization. Likelihood describes the probability or frequency a risk will occur over a specific time period.
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