A moving average makes it possible to smooth a series of values expressed as a function of time (time series). It makes it possible to eliminate the least significant fluctuations. Moving averages of order 3, 4, 5, etc. are calculated. The order is the number of periods (years, quarters, months, etc.) over which the moving average is calculated.
Practically, odd orders are preferred in order to avoid phase shift phenomena in the smoothed series. Thus, calculating the moving average of order 3 for a monthly turnover series over the period January 2001-January 2007 consists of calculating, for each month m, the average turnover for the three months m-1, m and m+1. The calculation is only possible from the second month of the series (in this case February 2001) to the penultimate month (December 2006).