This work studies the variance of the return over assets (ROA) of 1,664 Brazilian organizations between 1996 and 2003. This variance is divided into in factors associated with differences between business units, imdustries and economic conditions. The model is also calculated dividing the overall period into four year intervals so as to follow the evolution of the factors over the years. Results show that the main source of the variation in the performance can be attributed to differences among companies. The weight of this element increases over time. Surprisingly, considering the many and frequent crises suffered in the last couple of years, the role of the economic climate is slight and similar to that found by other authors for the American market.

O presente artigo analisa a variância do retorno sobre ativos (ROA) de 1664 empresas brasileiras entre 1996 e 2003. Nesse estudo a variância é dividida entre os fatores associados às diferenças entre as empresas, os setores em que elas se inserem e as condições econômicas do país. Os resultados do modelo foram, também, analisados dividindo o período total em intervalos de quatro anos, de forma a permitir a percepção de eventuais reflexos da conjuntura econômica do País sobre o desempenho das companhias. Os resultados mostram que a principal fonte de variação de performance pode ser atribuída a diferenças existentes entre as empresas e que o peso deste efeito se eleva ao longo do período estudado. Surpreendentemente, apesar das muitas e freqüentes crises pelas quais o País passou nos últimos anos, o efeito do contexto econômico sobre o desempenho das empresas mostrou-se pequeno, equivalente ao encontrado por outros autores que analisaram o caso de empresas situadas no mercado Norte-Americano.

This work studies the variance of the return over assets (ROA) of 1,664 Brazilian organizations between 1996 and 2003. This variance is divided into in factors associated with differences between business units, imdustries and economic conditions. The model is also calculated dividing the overall period into four year intervals so as to follow the evolution of the factors over the years. Results show that the main source of the variation in the performance can be attributed to differences among companies. The weight of this element increases over time. Surprisingly, considering the many and frequent crises suffered in the last couple of years, the role of the economic climate is slight and similar to that found by other authors for the American market.