Are there non linear relationships between the profitability of Portuguese services SMEs and its specific determinants?

Using quantile regressions, this paper examines the possibility of significant nonlinear relationships between the profitability of Portuguese service small- and medium-sized enterprises (SMEs) and its specific determinants. The results lead to the conclusion that there is a significant nonlinearity between specific determinants and profitability in Portuguese service SMEs. In the lower quantiles of the distribution of profitability of Portuguese SMEs, it is found that profitability on the one hand is catalysed by size, long-term debt and managerial control, and on the other hand, it is restricted by risk and research and development intensity. In the upper quantiles of the profitability distribution of Portuguese service SMEs, liquidity and research and development intensity serve as catalysers of profitability, while long-term debt restricts the level of profitability.