Bulletin 104, December 98 

One of the many duties we have as Operational Researchers is to promote the understanding and use of Operational Research. Not an easy task! We have seen our market position eroded and in some cases been overtaken by other disciplines. Nevertheless, it is never too late to undertake promotion.

An opportunity arose in England and was accepted. In the National Health Service in England 'letters' are sent by the central executive to chairmen/chairwomen of all health authorities. These letters cover many issues deemed important to the government and often exhort them to take action (for example Year 2000).

The letter was discussing the local balance between elective (planned admissions) and non-elective (emergency) demands for treatment. It was strongly suggested that simulation modelling was a useful tool in helping resolve the issues. Within the letter simulation modelling is defined as the building a replica of a complex system where alternative courses of action can be tried out using the model and their consequences can be assessed.

Most of the chairmen/chairwomen were not aware of what operational research is and what it could do for them; but in this letter they were exposed to one of our more commonly used techniques. The letter went on to describe the technique and some of the main points are given below.

The technique has also been used in many situations outside the NHS. Briefly three areas in which it has been used are: in retail banking, how many tellers should be on duty; in manufacturing industries, what is the most effective production planning method for planning the work in a job shop; in reservoir management, evaluating the impact of extreme and prolonged rainfall on the reservoir level and the best discharge procedures to ensure safety.

Simulation modelling can be used very flexibly. For example, it could be used to look at the organisation of a surgical Outpatient Clinic, the throughput of patients in a surgical ward or the care in the community of discharged surgical patients. But it could equally well join together these three elements and look at, in a single simulation model, the provision of a surgical service to meet the needs of the community.

The Health and Social Care services is an inter-related and inter-dependent system. The relations within this total system are as important for system performance as individual performance is. Within the total system there are many (sub) systems including systems of institutions, functions, problems and customers/stakeholders. The achievement of a total optimum within the overall system is not necessarily achieved by sub optimising each sub system independently.

We are thus led to consider the total system, the sub systems the relationships within, to ascertain what the best service might be. This is the 'systems thinking' approach.

The process of systems thinking has several objectives which include :

• the identification of interdependencies which shows how things fit together and what the links are between, eg how information flows within an health authority, how patients flow within a hospital
• to come to a shared understanding of problems for all people involved in an organisation so that there is minimal risk of ambiguity in discussions and that everybody is working from the same premises
• the identification of unintended consequences can be much improved when there is a more logical statement of the understanding of the problem
• the identification of points of high leverage, these are parts of the system where a change has a large impact which could be said to have a disproportionate effect
• the identification of problems requiring further analysis, again as there is a commonality of position this usually means that those problems become more obvious
• to undertake sensitivity analysis of proposed changes, to ensure that any solutions are robust and that any problems it could create in other parts of an organisation are identified.

With this approach the role of each sub system is more readily seen. The insights gained are invaluable in developing the structure of a simulation model. All relevant and important relationships can be included whilst still maintaining simplicity within the structure of the model. The validity of the model is therefore enhanced and the results will be more meaningful.

John Wilkes

Le Romandie Dom. Résidence
1884 Villars-sur-Ollon VD

Tel: +41 24 495 16 15
Fax: +41 24 495 16 15
wilkes.infor@com.mcnet.ch