Business cycles are intervals of expansion followed by recession in economic activity. They have implications for the welfare of the broad population as well as for private institutions. Typically business cycles are measured by applying a band pass filter to a broad economic indicator such as Real Gross Domestic Production. Here important problems may arise with a commonly used filter called the "ideal filter". For instance if a series is a purely random process without any cycle, an "ideal" filter, better called a block filter, a spurious cycle is produced as output. Fortunately methods such as [Harvey and Trimbur, 2003, Review of Economics and Statistics] have been designed so that the band pass filter may be adapted to the time series at hand [Harvey and Trimbur, 2003, Review of Econom