The PAT is a traditional method of trend detection originally developed by the NBER and is calculated as follows: Deviations from a 75-month centered moving average are first calculated; then, the obtained series is divided into expansion and contraction phases and the average is calculated for each phase; a three-phase centered moving average is calculated and these averages are interpolated.
10  BIS central bankers’ speeches  FCIXs may not be very sensitive to a revival of financial activity, because they are designed to detect signs of financial crisis. As the father of business cycle analysis, Arthur Spiethoff, pointed out, the timing of recoveries is often ambiguous, compared with that of crises.