Model Complexity Quotes

Remember that all models are wrong; the practical question is how wrong do they have to be to not be useful.

I remember my friend Johnny von Neumann used to say, 'with four parameters I can fit an elephant and with five I can make him wiggle his trunk.'

I think it is undeniably true that the human brain must work in models. The trick is to have your brain work better than the other person's brain because it understands the most fundamental models- ones that will do most work per unit.

In a single sentence the moral is: admit that complexity always increases, first from the model you fit to the data, thence to the model you use to think about and plan about the experiment and its analysis, and thence to the true situation.

In desperation I asked Fermi whether he was not impressed by the agreement between our calculated numbers and his measured numbers. He replied, "How many arbitrary parameters did you use for your calculations?" I thought for a moment about our cut-off procedures and said, "Four." He said, "I remember my friend Johnny von Neumann used to say, with four parameters I can fit an elephant, and with five I can make him wiggle his trunk." With that, the conversation was over.

The climate-studies people who work with models always tend to overestimate their models. They come to believe models are real and forget they are only models.

I hate big models.

Models can easily become so complex that they are impenetrable, unexaminable, and virtually unalterable.

Just as the ability to devise simple but evocative models is the signature of the great scientist so overelaboration and overparameterization is often the mark of mediocrity.

In the 1980s, there were occasions when it made sense to say, 'it is too difficult to maximize the likelihood function, and besides if we do, it will blow our model out of the water.'