Reading 1.4: Introduction to models
What gets you out of bed in the morning? In my case, the moment I hit consciousness, I scan my memory for any immediate tasks I need to achieve. Do I need to get the kids to school today? Have I got any early morning meetings? Identifying which task is relevant determines my subsequent actions. Still not fully awake, I start following a sequence of well-rehearsed steps aimed at getting the appropriate task done. These 'well-rehearsed steps' could be described as the model on which I base my actions.
You are all familiar with the idea of a model, a doll representative of a human or a toy car representative of a car. However, the word 'model' has a range of colloquial and technical interpretations, so I first need to establish the way in which I use the term. As a start, I would suggest that a model is a simplified representation of reality; the doll does not have all the features of a human, nor the toy car of the car. If when I got up in the morning and had to piece together all the various aspects which determine why I am following my particular sequences, I would never get anything done. So a simplified representation of reality is absolutely essential. But, what is reality? Without getting into deep philosophical water, it is important to recognise that in general, a model is usually a rather personal or subjective thing. It may be better to define it as a simplified representation of a person's or group's view of a situation.
I also need to stress that models are always intended for some purpose, and it is this purpose that decides how the simplification is made. The purpose of the doll, and the car perhaps, is to stimulate a child's imagination and help it become familiar with the world it will grow up into. The purpose of my 'getting out of bed' model is that it keeps me in right relation to both the physical world (the bed, stairs, breakfast, etc.) so that my body remains undamaged and properly fueled, and also to my social world (my family, employment, etc.) so that my social relations are maintained. Although you may not immediately think of them as such, you regularly use models in everyday life in order to achieve even the most basic task. For example, maps and plans are models of the layout of the roads, rivers, buildings or other features of our physical environment. An architect's sketch or an engineering drawing is a model of some artefact which is to be constructed. Its purpose is to communicate the design to those who will be building the artefact. Prior to constructing that artefact, we may be shown a scale model of it in order to test our reactions, or to see how it might operate. Photographs are models of the scene that the camera user saw when the shutter was pressed, perhaps taken to remind them of that special scene. Sculptures or paintings are also models, in that they are representations of some aspect of the world as it is interpreted by their creators, perhaps to make a particular statement to the world. The graphs and tables used to sell financial products are models of the expected performance of those products, and at the national level, government has a model of 'the economy' on which it bases decisions about tax rates, interest rates and other aspects of fiscal policy.
At a more fundamental level, the view I will take is that all our interactions with the world around us depend on our internal, mental models of how we perceive that world. It is worthwhile pausing for a moment to consider the importance of this. The preceding text has suggested several examples of different types of model to you, and at a very broad level, one of the purposes of this course is to introduce you to the sorts of model you are likely to use in thinking about systems that are different from those you habitually use. You have already seen how the ways in which we think and act are shaped by mental models, but as well as the internal representations discussed earlier, mental models also include language and linguistic models, in particular the metaphors that we use in thinking and talking about situations. Many of these are so common that we lose sight of the fact that they are just metaphors, such as 'getting to the heart of the matter', or 'the bottom line on this is ...'. Verbal models are important both as the external representation of our (internal) mental models, and probably as part of the thinking process itself.
Visual models too are extremely important. These models can be represented in two-dimensional and three-dimensional forms. Three-dimensional visual models usually use some physical material to represent physical aspects of a situation, as in scale models of new products or developments. For example, the shape or pattern may be similar, but the scale may be changed, or different materials may be used. Whichever is the case, there is usually a strong visual resemblance between the original and the model. There is also a wide range of two-dimensional representations which can be used in systems modelling. They include photographs, maps (see Figure 2) and plans, and other different sorts of two-dimensional diagrams such as sign graph diagrams (Reading 4.6) and system dynamics diagrams (Reading 4.7).
Quantitative (mathematical) models are models that can appear to be extremely powerful and sophisticated, and sometimes, 'modelling' is taken to imply only mathematical models. They make use of mathematical techniques to calculate numerical values for the properties of the defined system, and can be used to explore the results of different possible actions.
These different forms of modelling all require different skills, or as described in an earlier resource reading, multiple intelligences. Simplified representations of people's views of a situation can be communicated using all three modelling approaches, each having particular roles to play in particular circumstances.