Confidence Indexes are summary numbers measured by the FGV./IBRE., determined by the sum of the differences (in percentage points) between the extreme answer options of the questions in each research.  These options are, for the most part, of a qualitative type (for example, “the situation is good/normal/bad”, or “the situation will be better/same/worse”).

To the result of that subtraction, the value of one hundred points (100) are added so that the indexes can vary from 0 to 200 points.

The indexes are normalized with an average of 100 points and a standard deviation of 10 points, based on the period between July 2010 and June 2015.