Analysing the Business Model
A large safety case or Hazard Log consists of thousands of elements with complex interdependencies. Identifying areas which are affected by a change or a challenge costs time and money.
The DSM uses queries and matrices to analyze GSN & Bowtie diagrams, FMEAs and Hazard Logs. It present the results in a clear and easily understood format. You can quickly identify what has changed, what is affected by a change and what needs to be done to keep the safety case up to date and valid.
Queries interrogate the DSM diagrams or in the case of Hazard Logs and FMEAs - the DSM Entities, to ascertain the information required. They are defined using a simple diagram notation and can follow the flow of a GSN network or interrogate the data sitting in the fields of any DSM entity. Because they capture information, they are the building blocks for Matrices and Reports. The ‘Input’ module will allow you to point a query at a certain place in the Model Tree as your starting point. It is also used to take an input from a previous query in a Matrix. Queries will always finish with an ‘Output’ where the result of the analysis will appear.
A typical Safety Case Argument could have thousands of GSN diagrams and each diagram will contain many individual GSN elements. A query allows you to point it to a starting point anywhere in the Model Tree and queries can be exported to other DSM files or imported from them. Effect use of 'Packages' in the Model Tree will assist in targeting Queries correctly.
Queries can answer the business questions such as 'When was the Safety Case last updated?' or 'What has changed in the Hazard Log during the last 10 days?' Some more examples for business questions are given below.
Business question Examples
Matrices provide the information output from queries in tabular form. A matrix structure is defined with queries and data fields . They can be used to provide risk/hazard registers, project data summaries or a detailed analysis of a GSN diagram in the Safety Case.