Uma realidade heterogénea. muito mais complexa do que nos pintam

Neste postal "Lugar do Senhor dos Perdões (parte III)" escrevi:
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"Quando os macro-economistas falam sobre o desempenho, sobre a produtividade de um sector de actividade, como o calçado, como o têxtil, como o mobiliário, falam de um bloco homogéneo, coerente, maciço... como se todas as empresas, imersas no mesmo ambiente competitivo, tivessem o mesmo comportamento"
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Pois bem, acabo de descobrir este artigo "Measuring and Analyzing Aggregate Fluctuations: The Importance of Building from Microeconomic Evidence" de John Haltiwanger:
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"A pervasive finding in recent research using longitudinal establishment level data is that idiosyncratic factors dominate the distribution of output, employment, investment, and productivity growth rates across establishments.
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Seemingly similar plants within the same industry exhibit substantially different behavior on a variety of measures of real activity at cyclical and longer-run frequencies. In the fastest-growing industries, a large fraction of establishments experience substantial declines, whereas in the slowest growing industries, a large fraction of establishments exhibit dramatic growth."
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"The observed tremendous withinsector heterogeneity raises a variety of questions for our understanding and measurement of key macro aggregates. Much of macroeconomic research and our measurement of aggregates is predicated on the view that building macro aggregates from industry-level data is sufficient for understanding the behavior of the macroeconomy. The implicit argument is that, at least at the level of detailed industry, the assumption of a representative firm or establishment is reasonable.
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the accumulating evidence from recent establishment-level studies of employment, investment, and productivity growth suggests that this canceling out is far from complete. It is becoming increasingly apparent that changes in the key macro aggregates at cyclical and secular frequencies are best understood by tracking the evolution of the cross-sectional distribution of activity and changes at the micro level."