A Toast to Complexity
Ever wonder why financial forecasts by economists seem about as
reliable as weather forecasts by meteorologists? The simple answer:
Predicting economic and weather systems ain't easy. British economist John Kay offers a more extensive
answer in yesterday's Financial Times. Here's an abbreviated version
of the
article :
[E]conomic prediction is hard. National economies, financial markets and businesses are complex, dynamic, non-linear systems. Your economy contains many people and many agents, and there are many interactions between them.Like it or not, the global economy has never been as complex as it is today. That is surely not comforting to those who prefer certainty, yet such complexity means opportunities for traders looking in the right places and the right times. As the economically historic year of 2008 comes to a close tonite, I will drink a toast to complexity and recall the words of the late American computer scientist Alan Perlis:
Many of [the successes of the natural sciences] have been achieved because the problems of physics often involve objects large enough to be studied individually - the motion of the earth, for example. Or components small enough to be subject to statistical regularities - we can never predict the behaviour of an individual molecule or electron, but there are so many molecules and electrons that for most purposes it does not matter. Many of the phenomena we deal with in economics and business fall in between - the units of analysis are individualistic but also too numerous for their idiosyncrasies to be individually understood.
Economic systems are also dynamic. Dynamic in the sense that they evolve - which makes the mathematics harder. But also dynamic in the sense that the structural relationships constantly change.
[T]he killer is that dynamic complexity interacts with non-linearity...small differences in initial conditions can have dramatic differences in ultimate outcomes. The problem is often expressed through the metaphor of the butterfly which, by flapping its wings on one side of the world, sets in train a chain of consequences that results in a tornado many thousands of miles away.
The nature of such complex, dynamic, non-linear systems is that we may be able to say a lot about their general properties, while being unable to make specific predictions. You will recognise this characteristic in the work of your Meteorological Office, which can tell you fairly reliably when spring will follow summer, or how much cooler or warmer it will be when you visit far-flung outposts, but which can never predict what the weather will be more than a few days ahead, or even with certainty what it will be like tomorrow.
The market for clairvoyance has existed through history and is satisfied by messages based on hope and ambiguity. The market for economic prediction is similar. Successful proponents are distinguished by their television manner rather than the accuracy of their forecasts.
Shakespeare, traducing Richard III with the connivance of the first Queen Elizabeth, understood better than anyone that a good story is more compelling than the search for truth. The American political scientist, Philip Tetlock, has studied the prognostications of pundits over several decades. He finds that the better known the forecaster, the less accurate the forecast. Business people, politicians and journalists value clarity and certainty of view more highly than acknowledgement of the uncertainty of a complex world. But it is mostly people who appreciate that complexity who have worthwhile things to say about the future.
"Fools ignore complexity. Pragmatists suffer it. Some can avoid it. Geniuses remove it."





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