Heterogeneidade e produtividade

"In his Nobel lecture, James Heckman named 'the evidence on the pervasiveness of heterogeneity and diversity in economic life' the most important empirical discovery from econometric analyses using micro data. Everybody who has ever worked with plant- or enterprise-level data will agree - there is no such thing as a representative firm, not even in four-digit industries where growing and shrinking, entering and exiting firms can be found in each period. Productivity differentials are a case in point as regards firm heterogeneity within industries. 'Of the basic findings related to productivity and productivity growth uncovered by recent research using micro-data, perhaps most significant is the degree of heterogeneity across establishments and firms in productivity in nearly all industries examined'." [Moi ici: Como não recordar o Lugar do Senhor dos Perdões ou Voltar ao Lugar do Senhor dos Perdões]

Seguem-se agora uns trechos que explicam o mindset das polítcas bem intencionadas:

"The empirical facts uncovered in microeconometric studies motivated formal models for the dynamics of industries with heterogeneous firms

...

In these models, productivity differentials play a central role in the entry, growth and exit of firms. In equilibrium, growing and shrinking, exiting and entering firms that have different productivities are found in an industry.

...

[Moi ici: Os políticos gostam de estabilidade, receiam a incerteza. Vêem com maus olhos o encerramento de empresas] H1. Firms that exit in year t were less productive in t-1 than firms that continue to produce in t.

Given that firms with a low productivity have a higher probability of exit at a point in time, exiting firms will be concentrated among the least productive units. [Moi ici: Por isso, os políticos pensam que as empresas com baixa produtividade têm de ser subsidiadas, têm de ser apoiadas, para que não encerrem. A desculpa é a de que os apoios ajudarão as empresas a aumentarem a sua produtividade] 'Less productive' means that the productivity distribution of exits is stochastically dominated by the productivity distribution of the continuing firms.

H2. Firms that enter the market in year t are less productive than incumbent firms in year t.

This follows from the selection process described above that leads to an improvement of the productivity distribution of incumbents over time because in each period the less productive firms have the highest probability to fall below the critical level and, therefore, to exit. Here, 'less productive' means that the productivity distribution of entries is stochastically dominated by the productivity distribution of incumbents.

H3. Surviving firms from an entry cohort were more productive than nonsurviving firms from this cohort in the start year."

Não me custa nada a crer no poder estatístico de H1, H2 e H3 no texto acima numa economia de mercado. Isto ajuda a explicar o aumento da produtividade agregada num dado sector económico. No entanto, não ajuda a explicar o mais importante.