# Knowledge Base & Community Wiki

## What Are The Various Modelling Approaches Available

Generally speaking there are three main modelling approaches which are used commonly across the industry to model system performance and understand the behavior of the system for various change in input parameters. Let’s look at the three modelling approaches.

**Analytical Models** – Analytical models are mathematical models that have a closed form solution, i.e the solution to the equations used to describe changes in a system can be expressed as a mathematical analytical function. An Analytical model is simply a mathematical equation that describes relationships among variables in a historical data set providing the user with a set of equations that can be used to forecast the behavior of the system. Analytical models include Response Time Theory, Queuing Theory, Universal Scalability Law, Workload Model and Little’s Law.

**Statistical Models** – A statistical model is a set of assumptions concerning the generation of the observed data, and similar data from a larger population. The model represents, often in considerably idealized form, the data-generating process. A statistical model uses industry standard statistical modelling techniques to identify relationships between variables in the dataset and provides user with a set of re-usable equations that can be used to forecast the behavior of the system. Statistical models include Curve fitting techniques (Linear regression curves, Logarithmic regression curves, etc.), Time Series Decomposition, Time Series Forecasting (ARIMA modelling, etc.).

**Simulation Models** – A Simulation Model is a mathematical model that calculates the impact of uncertain inputs and decisions we make on outcomes that we care about , such as profit and loss, investment returns, environmental consequences , and the like. Simulation Modelling is used to help designers and engineers understand whether, under what conditions, and in which ways a part could fail and what loads it can withstand. Simulation models include Discrete Event Simulation, Markov’s Chain based State Space simulations, etc.

Hopefully this article has introduced you to the different Performance modelling techniques used across the industry.

**Modelling Solution:** VisualizeIT offers access to a bunch of Analytical Models, Statistical Models and Simulation Models. Access to all the Analytical (Mathematical) models is free. We recommend you try out the Analytical models at VisualizeIT which are free to use and drop us a note with your suggestions, input and comments. You can access the VisualizeIT website here and the VisualizeIT modelling solution here –VisualizeIT.