2014年-ECB欧洲央行_The_Phillips_curve_relationship_in_the_euro_area_16页_326kb

THE PHILLIPS CURVE RELATIONSHIP IN THE EURO AREA: A SUMMARY

Core Content

The Phillips curve is a widely used framework that links inflation to economic slack, such as the output or unemployment gap. It provides a conceptual basis for understanding and forecasting inflation dynamics. However, the Phillips curve is not a single, fixed relationship; rather, it encompasses various specifications, each with different assumptions and measures of economic slack and inflation.

The article focuses on the Phillips curve relationship in the euro area since 1999, with a particular emphasis on the period from 2008 onwards, marked by the financial and sovereign debt crises. These crises led to prolonged economic slack, characterized by negative output gaps and high unemployment gaps. Theoretical and empirical analyses suggest that such conditions should lead to lower inflation, yet the actual relationship between inflation and economic slack has shown considerable uncertainty and variation across countries.

Main Points

• Conceptual Uncertainty: The Phillips curve is not a single concept, but a set of plausible specifications. Different measures of economic slack (e.g., unemployment gaps, output gaps, real unit labour costs) and inflation expectations can influence the relationship.

• Empirical Uncertainty: The relationship between inflation and economic slack is subject to significant uncertainty, especially in real-time data. The use of output and unemployment gaps as proxies for economic slack is based on estimates that are often revised and methodologically sensitive.

• Forecasting Limitations: While the Phillips curve can be a useful tool for cross-checking inflation developments with output and demand, it is not sufficient for accurate forecasting. The complexity of the inflation process, including supply-side shocks and inflation expectations, means that the curve alone cannot capture all factors affecting inflation.

• Country-Level Heterogeneity: The euro area is heterogeneous in terms of economic structure and institutional frameworks. As a result, the Phillips curve relationship varies across countries, with some showing strong responsiveness and others weak or even negative coefficients.

• Impact of Crises: The financial and sovereign debt crises significantly affected the Phillips curve relationship. For the euro area as a whole, the impact of economic slack on inflation has weakened, while for some countries, it has strengthened, possibly due to structural reforms and reduced nominal rigidities.

Key Information

• Inflation Measure: The analysis uses HICP inflation excluding energy and food, as it is less influenced by commodity prices and better reflects domestic price pressures.

• Regression Framework: The Phillips curve is often estimated using a regression model such as:
  $$
  \pi_{\mathrm{t}} = \alpha + \beta \pi_{\mathrm{t - 1}} + \gamma \mathrm{gap}{\mathrm{t - 1}} + \varepsilon{\mathrm{t}}
  $$
  where $\pi_{\mathrm{t}}$ is the annualised quarterly rate of HICP inflation, $\pi_{\mathrm{t - 1}}$ represents inflation persistence, and $\mathrm{gap}_{\mathrm{t - 1}}$ is a measure of economic slack.

• Impact Coefficients: Chart 2 illustrates the range of one-year impact coefficients of different slack measures on inflation, showing marked heterogeneity across countries. The cumulative one-year impact is calculated as $\gamma (1 + \beta + \beta^2 + \beta^3)$.

• R² Coefficients: Chart 3 presents the range of in-sample fit measures (R²) for the Phillips curve across countries, highlighting that the goodness of fit varies significantly, and no single measure of slack consistently outperforms others.

• Structural Reforms: Structural reforms in labour and product markets have played a role in altering the Phillips curve relationship, potentially reducing price and wage rigidities and increasing the responsiveness of inflation to economic slack.

• Supply-Side Factors: The article notes that factors such as indirect taxes, administered prices, and import prices (especially energy prices) can influence inflation independently of economic slack, complicating the Phillips curve relationship.

• Non-Linearities and Instabilities: The relationship between inflation and economic slack can be non-linear, especially in periods of persistent slack, where inflation may not decline significantly despite high unemployment or low output.

Conclusion

The Phillips curve remains a useful but limited tool for analyzing inflation in the euro area. While it provides insights into the relationship between inflation and economic slack, its empirical validity is subject to considerable uncertainty and cross-country variation. The financial and sovereign debt crises have further complicated this relationship, with mixed effects across the euro area. Therefore, the Phillips curve should be considered as one element within a broader policy analysis framework.