RDP 2005-05: Underlying Inflation: Concepts, Measurement and Performance Equation

{\hat{π}}_{t}^{*} = {\frac{\sum_{i = 1}^{N} \frac{w_{i t}}{{\hat{σ}}_{i}^{2}} π_{i t}}{\sum_{i = 1}^{N} \frac{w_{i t}}{{\hat{σ}}_{i}^{2}}}}_{.}