From this website:
http://mises.org/about/3224
Austrian economists realize that the future is always uncertain, not radically so, but largely. Human action in an uncertain world with pervasive scarcity poses the economic problem in the first place. We need entrepreneurs and prices to help overcome uncertainty, although this can never be done completely.
Forecasting the future is the job of entrepreneurs, not economists. This is not to say that Austrian economists cannot expect certain consequences of particular government policies. For example, they know that price ceilings always and everywhere create shortages, and that expansions of the money supply lead to general price increases and the business cycle, even if they cannot know the time and exact nature of these expected events.
Government Numbers
One final area of theoretical concern that distinguishes Austrians from the mainstream is economic statistics. Austrians are critical of the substance of most existing statistical measures of the economy. They are also critical of the uses to which they are put. Take, for example, the question of price elasticities, which supposedly measure consumer responsiveness to changes in price. The problem lies in the metaphor and its applications. It suggests that elasticities exist independent of human action, and that they can be known in advance of experience. But measures of historical consumer behavior do not constitute economic theory.
Another example of a questionable statistical technique is the index number, the prime means by which the government calculates inflation. The problem with index numbers is that they obscure relative price changes between goods and industries, and relative price changes are of prime importance. This is not to say the Consumer Price Index is irrelevant, only that it is not a solid indicator, is subject to wide abuse, and masks highly complex price movements between sectors.
And the Gross Domestic Product statistic is riddled with composition fallacies inherent in the Keynesian model. Government spending is considered part of aggregate demand, and no effort is made to account for the destructive costs of taxation, regulation, and redistribution. If Austrians had their way, the government would never collect another economic statistic. Such data is used primarily to plan the economy.
From “Bogart” on this forum:
No, no aggregate measures of the economy make sense and are fudged wildly by the honest federal employees who assemble them. The economy is not a bunch of aggregates but the product of a huge number of transactions entered into freely by a giant number of people.