Inflation differentials in the euro area: size, causes, economic policy implications and relative position of Belgium

Both the size and the persistence of inflation differentials in the euro area have been the subject of a large number of studies in recent years. These studies have tried to determine the causes of these differentials as well as their implications not only for the implementation of the common monetary policy but also in terms of the macroeconomic policies needed at the country level. Indeed, since the start of Stage Three of the EMU, countries can no longer correct country-specific imbalances or idiosyncratic shocks through changing their national monetary policy stance. As a consequence, it may be deemed fit, in some cases, to take appropriate policy measures aimed at reducing inflation differentials. The article tackles the case of Belgium, in which country the inflation differentials vis-a-vis the euro area appear to be relatively small and do not seem to show any persistence or any systematic upward or downward bias. However, empirical studies based on the “Balassa-Samuelson” theory have concluded that Belgium should be prone to a relatively high inflation rate. This theory holds that, on restrictive assumptions, a real appreciation (or positive inflation differential) is generated in countries showing the most rapid growth of the productivity differential between the traded and non-traded goods sectors. The article goes into those rather surprising results. The authors observed a pronounced increase of relative productivity in Belgium and a strong positive correlation between relative productivity and relative prices, measured by the value added deflator, which proves to be consistent with the theory and the results of previous studies. These studies have typically assumed that the tradable sector showed purchasing power parity. In that case, the pronounced increase in relative prices has strong implications for the real exchange rate (or inflation differentials). However, the authors found empirical evidence against this hypothesis in the Belgian case. Indeed, the real exchange rate in the tradable sector depreciated strongly in the seventies and the early eighties. This depreciation in the tradable sector offset the impact of the positive relative price differential, causing the real exchange rate for the economy as a whole to be relatively stable. Belgium should therefore not be an economy prone to high inflation. As the HICP is the main indicator monitored by the European monetary authorities, it was important to examine whether such conclusions could also be drawn for the consumer price index. The authors found similar results, namely a stable real exchange rate for the Belgian economy as a whole during the period under review and, therefore, the absence of any structural reason for inflation to be systematically higher in Belgium. It may thus be concluded that significant and persistent inflation differentials between Belgium and the euro area or a systematic bias in any particular direction are unlikely and, therefore, that the European monetary policy is appropriate for the Belgian economy in the current environment.