d) The fourth principle is the need to monitor unit labour costs and national competitiveness indicators to prevent or correct abnormal deviations where necessary. We would expect some dispersion and differentials among euro area countries. As I have already mentioned, in such a vast area there will always be some diversity, as in the United States.
Countries catching up in terms of GDP per capita and price levels are always likely to have stronger output growth and higher inflation. Diversity may also extend to correcting past excesses in terms of overall cost and price competitiveness, particularly in the tradable goods and services markets.