Setting impact and likelihood definitions

Risk criteria typically include definitions of different levels of impact and likelihood, such as those shown below. Impact refers to the severity of a problem, for example whether it causes death, injury or merely a delay. Likelihood refers to how likely or probable it is that the problem will occur, for example it may be extremely unlikely or very likely. The definitions are used when assessing a risk to give numerical scores to its impact and likelihood, which are usually rated between 1 and 5. Risk scores can then be calculated by multiplying the two values together, giving a maximum possible score of 25. Both impact and likelihood are explained further in the Analyse risk activity.

Excerpt from a set of impact definitions in the domain of ‘Impact on the safety of patients, staff or public (physical/psychological harm)’ (from A risk matrix for risk managers)

Excerpt from a set of likelihood definitions using broad descriptors of frequency (from A risk matrix for risk managers)

 

As mentioned above, risk criteria are often set by NHS Trusts. However, if Trust risk criteria are not available, then a full set of criteria that can be used in healthcare projects is provided in A risk matrix for risk managers, available from the NHS National Patient Safety Agency (a body which has now been transferred into NHS England). Some examples of criteria are also given above. However, note that these are not complete.

Putting ‘Setting impact and likelihood definitions’ into practice

Space to record this information is provided in the SSA Assessment Form. To do this: Select the ‘Set risk criteria’ page in the Assessment Form. List any risk criteria documents and guidelines that need to be referred to in the box headed Documents. Other documents relevant to the assessment could also be noted in this box. These might include other policies, procedures or reports. Case Study The completed ‘Set risk criteria’ page from the Section 136 case study is shown opposite. Further explanation of this stage in the case study can be found on the Section 136 page about Setting impact and likelihood definitions. Click to enlarge Click to download PDF for full case study

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Setting the risk bands

The risk criteria also contain information on what types of action are required for different risk scores. This is often presented by grouping risk scores into bands and colour coding them, as in the example below. Different Trusts may use different numbers of bands and different colours, although red is typically used for high risks. For such risks, the risk criteria may mandate that actions be taken to lower the risks. Green is usually used for lower risks that may not require immediate action.

Example of risk criteria from a risk assessment procedure document (Image courtesy of Cambridge University Hospitals NHS Foundation Trust)

As mentioned above, risk criteria (including risk bands) are often set by NHS Trusts. However, if Trust risk criteria are not available, then the bands listed in the example above could be used. Alternatively, a full set of criteria that can be used in healthcare projects is provided in A risk matrix for risk managers, available from the NHS National Patient Safety Agency (a body which has now been transferred into NHS England).

Putting ‘Setting the risk bands’ into practice

Space to record this information is provided in the SSA Assessment Form. To do this: Select the ‘Set risk criteria’ page in the Assessment Form. Describe the criteria that will be used to categorise the risk scores in the box headed Risk bands. In the spreadsheet verson of the form, replace the descriptions of the colour bands with the definitions that you wish to use. These will be then used to automatically colour-code the risk scores later in the SSA. Alternatively, remove this if you do not want to use automatic colour coding. Case Study The completed ‘Set risk criteria’ page from the Section 136 case study is shown opposite. Further explanation of this stage in the case study can be found on the Section 136 page about Setting risk bands. Click to enlarge Click to download PDF for full case study

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