What's a model?

There are lots of types of models! The type that the PMN deals with are scientific models. These models are representations- of a system, or a phenomenon in the world- which scientists build to help think and reason about it, know more about how it works, and solve problems relating to it. There are MANY types of scientific models, but the kind that PMN deals with are computer models. This means scientists use a computer to build the representation, and then use the computer's output to think and reason about different problems.

Here's just one example: imagine an emergency room. An ER is a complicated system, with people coming in and out, needing different services, and looking to accomplish many different goals (e.g., keep waiting times down, optimize various health outcomes, and so on). It would be very hard to understand every aspect of an ER by just thinking about it in your head. By building a computer model of an ER, scientists can think about different relevant questions and get better answers to them- like, how many people tend to come to a certain ER on different days, at different times? What services do they tend to need? So how many different specialists should be working at a particular time? And so on. We should point out that to build a model, scientists generally need information (also called data, or evidence) to put in it (this leads to another question about how models are built, which we will leave for another time). Anyway, this is just an example- but it helps show what we mean when we say "a computer model is a representation that scientists use to think through problems". If you have further questions, let us know!