The last two weeks we have been looking at the problems with models. First we touched on what I called the Economic Singularity. In physics a singularity is where the mathematical models no longer work. For example, models based on the physics of relativity no longer work if one gets too close to a black hole. If we think of too much debt as a black hole of sorts, we may understand why economic models no longer work. Last week, in “The Perils of Fiscal Cliff,” we looked at the use of fiscal multipliers by economists in order to argue for or against governmental economic policies. Do you argue for austerity, or against it? There is a model that will support your case, most likely using the same data that your adversary uses.
These letters have generated a great deal of positive response and conversation. While I very rarely suggest to readers to go back and read previous letters, but reading these may help you appreciate why it is so difficult to understand what is happening in the global economy today.
This week, in a somewhat shorter letter, we once again consider the vagaries of measurements and models. Growth of the US economy, we are told, was 2% last quarter. That number will of course be revised, but what is it we are measuring? Should we attach any importance to the measurement at all? The short answer to the last question is yes, but it is important to understand that there is no certainty in that number. Or at least not any certainty according to the generally accepted meaning of that word.