Firms’ productivity and their international expansion. The case of Lodz voivodeship

The article presents results of research on relation between productivity of firms from Lodz Voivodeship and their international expansion by exports, imports of intermediate and capital goods and foreign direct investment (FDI). It has been proved, that firms engaged in international activities are more effective, especially firms conducting FDI are the most productive. Two main hypotheses of the so called New New Trade Theory were tested: the self-selection hypothesis (high productivity leads to internationalisation) and the learning- -by-doing hypothesis (internationalisation leads to increase of productivity). The self-selection among region’s firms was proved. On the other hand, the results concerning learning effects turned out to be statistically insignificant. However, due to drawbacks of available data, there are premises for not unequivocally rejecting the learning-by- -doing hypothesis