Models & Manifesto

Have you ever heard anyone say that their car got lost? Or that they got into a massive pile-up because it was a 1-in-200-year event that someone drove on the wrong side of a highway? Probably not.

But statements similar to these have been made many times since mid-2007 by CEOs and risk managers whose firms have lost great sums of money in the financial crisis. And instead of blaming their cars, they blame their risk models. In the 8 February 2009 Financial Times, Goldman Sachs’ CEO Lloyd Blankfein said “many risk models incorrectly assumed that positions could be fully hedged . . . risk models failed to capture the risk inherent in off-balance sheet activities,” clearly placing the blame on the models.

But in reality, it was, for the most part, the modellers, not the models, that failed. A car goes where the driver steers it and a model evaluates the risks it is designed to evaluate and uses the data the model operator feeds into the model. In fact, isn’t it the leadership of these enterprises that are really responsible for not clearly assessing the limitations of these models prior to mass usage for billion-dollar decisions?

But humans, who to varying degrees all have a limit to their capacity to juggle multiple inter-connected streams of information, need models to assist with decision-making at all but the smallest and least complex firms.

These points are all captured in the Financial Modeler’s Manifesto from Paul Wilmott and Emanuel Derman.

But before you use any model you did not build yourself, I suggest that you ask the model builder if they have read the manifesto.

If you do build models, I suggest that you read it before and after each model building project.

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Explore posts in the same categories: Assumptions, Basis Risk, Black Swan, Enterprise Risk Management, ERM, Modeling, Random, Risk, risk assessment, Stress Test, Tail Risk, Uncertainty, VaR, Volatility

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