Comparisons are often difficult even at a national level, let alone the European level, even though the goods and services on offer across the EU are similar, and even though a fair number of them are now traded across borders.
Jättes kõrvale Euroopa tasandi, on andmeid isegi riiklikul tasandil keeruline võrrelda, kuigi tooted ja teenused, mida Euroopa Liidus pakutakse on sarnased ning suur osa neist turustatakse piiriüleselt.