Modelling complex systems

I'm yet to finish my Chapter 9 reading, but I thought I would post an idea from Chapter 9 which is probably more widely applicable.

At the beginning of Chapter 9 of Nelson, it is argued that when studying a system which has a large number of constituents which are allowed to interact - such as a biological system - the analysis of the system can be greatly simplified, using just a few degrees of freedom to effectively describe a system's behaviour.

So when you have a large interacting system - our analysis can be made more simple if we first stop to think about what are the parameters that we can use that will more widely describe the bulk behaviour of the system. I think that at times this might seem like an oversimplification, but I think when analysing a large complicated system, we need to think about what questions we're really trying to answer, and what parameters are the most important that will allow us to answer that question. If you tried to take everything into account, then at times it's going to take far too long and will be far too complex to model, when some of the minor details may not matter when trying to answer a particular question about your system.