sexta-feira, 5 de dezembro de 2008

Como manipular a estadística

Jim Jubak: "... Most criticism of the official inflation number, the Consumer Price Index, or CPI, has focused on the statistical flimflam used by the Bureau of Labor Statistics to calculate how fast prices are going up. Chief among these is a technique called hedonics. Starting in the 1990s, some economists and government statisticians began arguing that a $100 increase in the price of, say, a car wasn't really a $100 price increase if the power, safety features or general usefulness of the car improved substantially. If the subjective value of the car went up by $100, then, despite the increase in what you paid, according to the government, the price didn't go up at all. The objection to this kind of adjustment is that it introduces a huge amount of subjectivity into the process of calculating inflation. Determining the increased usefulness of a product or service requires a subjective judgment about the value of this or that feature. What is the extra horsepower of a car worth to a user? How about extra safety features? And to which user? And if the cost of a car went up by $100 even if it came with more and better features, wasn't the price still in reality $100 higher? Hedonic quality adjustments weren't the only statistical adjustments that the government made to the inflation numbers. Starting in 1983, the government also started to measure changes in the cost of housing by looking not at the cost of a house but at what an owner would get if he or she rented out that house. Since in a housing boom the price of houses rises about three times as fast as rents do, this change understated the rate of inflation. In the 1990s, the government also started to include substitution pricing in its inflation measure. In this adjustment, government statisticians assumed that if the price of something went up, people would use less and would substitute a less costly product or service. So when steak went up in price, consumers might buy more pork or chicken. Figuring out what substitution a consumer would make again added to the subjectivity of the inflation numbers. Including substitution destroyed the whole point of the exercise because it turned the government's shopping basket from an inflation measure to a set of lifestyle choices..." http://articles.moneycentral.msn.com/Investing/JubaksJournal/fake-inflation-numbers-masked-crisis.aspx?page=all Veja tambem: http://www.mises.org/story/1873 Tarefa: Investigue as consequencias de um metodo de calculo que resulta em taxas de inflaçao mais baixas para outras indicadores econômicos, especialmente taxa de crescimento e produtividade.

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