measurement and analysis of industrial relations aggregates: what is the relevant unit of analysis in comparative research?

There is a long tradition in comparative research on industrial relations of analysis concentrating on differences and similarities between countries, that is, focusing on aggregates measured at the national level. But what happens if there are no (more) differences in industrial relations systems between countries? If there are not differences the question arises if comparative research is becoming meaningless? Concentrating predominantly on statistical and methodological aspects, it is argued in this article that over recent decades industrial relations systems have changed in such a way that the national level has become less relevant as a unit of analysis. It is explained that this development in the nature of the field affects the measurement of its indicators which form the backbone of any comparison. On the basis of an empirical comparison of key industrial relations indicators in the European Union member states, it is concluded that comparative research has not reached a dead end, but rather that the field might have to reconsider the relevant unit for analysis. It is shown that the relevant unit for analysis has shifted increasingly from the national towards the sectoral level. One consequence of this shift is that from a methodological perspective comparisons between sectors, rather than between countries, are nowadays often more informative.