Summary

In this lesson, we have identified and defined what a model is. Understanding systems does not stop with our particular field. Looked at models in broadest sense and when/how best to apply particular model. Importance of verification and validation.

Steps to take when modelling

Brief overview of steps for tackling modelling process. What precisely is our problem and what do we want the model to do? Do we need a model at all? Perhaps it is too simple a task and we would sooner not waste time. Are similar models available? Can we buy one or use a pre-existing in-house one? Danger is discovering […]

Metaphors

Form of model used by humans to communicate. Still a form of abstraction. Used to represent something but not in literal sense – putting a complex explanation into simple terms. Examples: Food for thought Something that warrants serious consideration Lions lead by Donkeys German High Command description of the British Army in World War 1 A bird in the hand […]

System walkthrough and Consistency testing

System walkthrough Explaining model to another person/persons – enables modeller to focus on different aspects and to discover problems. Writing system documentation can have the same effect to by making to modeller look at model from different perspective. Consistency testing Check model produces similar results for input parameter values that have similar effects. Example: Network with two inputs, each with […]

Model Validation and Verification

Model is abstraction & consists of assumptions we make. In creation we remove unnecessary detail ¬†and focus on elements of system that are in important from desired performance point of view. Assumptions about system must be made during model construction therefore we must check that the model is a good fit. Process of robust model required two parts: design and […]

A framework for models

Many different types of models but Ackkoff (1962) proposes three categories: iconic model – expected to behave same as real thing. e.g. scale model of ship or model aircraft in wind tunnel. analogue model – attempt to simulate behaviour without necessarily replicating physical appearance. e.g. computer games like Forza and FIFA. analytical model – developed from mathematical or logical relationships […]

Model Definition

Useful when considering situation without losing holistic viewpoint, example of modelling is boundary and environment diagram. The type of model used should be the best suited based on our understanding of the situation. A model is an abstraction of reality, to abstract is to summarise. Models are created because: Real life is complex – not just black and white but […]

Models

Identify and define what a model is, also when and how best apply a particular model. “Model” can be used in different contexts to mean different things e.g.: The model, although not to scale, lets us see how the planets orbit the sun. The super model was demonstrating the latest fashions at the show. The model railway is an exact […]