Economic Computation and Economic Cybernetics Studies and Research, Issue 1/2016, Vol. 50 _________________________________________________________________________________ 5 Professor Moisă ALTĂR, PhD E-mail: altarm@gmail.com The Bucharest University of Economic Studies The Romanian - American University– FINSYS Ana-Maria CAZACU (BANCU), PhD Candidate E-mail: ana02mary@yahoo.com The Bucharest University of Economics Studies TESTING SELF-SELECTION AND LEARNING BY EXPORTING HYPOTHESES. THE CASE OF ROMANIA Abstract. This paper provides empirical evidence of export-productivity link, using a comprehensive set of data on Romanian firms activating in ten business sectors. By using the semi-parametric estimation technique developed by Levinsohn and Petrin (2003) to estimate Total Factor Productivity (TFP)we find that exporters display a productivity advantage compared to their domestic counterparts. We seek to distinguish between self-selection and learning by exporting through matching techniques and we find that the most productive firms self-select in activities in international markets, including importing. Learning effects (when TFP is used as outcome) are present on a narrow sample of companies, although in most of the cases are positive and significant when using labour productivity. Stronger evidence for positive effects of international trade is found for importers, which suggests a possible learning by importing phenomenon manifested in Romanian. Keywords: endogeneity, selection bias, TFP, semi-parametric models, matching techniques, propensity score JEL Classification: C23, D24, F10, F23, F61 1. Introduction and state of art Both academics and policy makers has increasingly focused in recent years on understanding the role of firm-level competitiveness and efficiency indicators in determining aggregate results (Competitiveness Research Network, 2014). Particularly, assessing the main drivers of international sales and the impact of the increased international trade on micro-level performance is of vital importance for a small and open economy. The literature centred on the link between involvement in export activities and firms’ performance is focused on testing two main hypotheses: self-selection and learning-by-exporting. Self-selection hypothesis relies on the idea that companies entering export markets have higher productivity