A Central Bank that achieves and maintains its objective of a low and stable inflation rate, and does not attempt to exploit the trade-off between real output and inflation is defined to be credible. A time series model was estimated in order to verify the brazilian inflation target regime's credibility. At the same time, a monetary policy's credibility index was built upon a State-Space model. In this model a random coeficients Kalman filter model of the inflation-output trade-off indicates the evolution in the credibility of the brazilian Central Bank as an inflation fighter.
