Note that in Simple Moving Average table, the average of numbers n, n+1 and n+2 in the "Original Values" column (where "n" refers to the row position) is placed in row position n+2 of the "3-Month Simple Moving Average" column. This Moving Average display technique is known as "Trailing Averages". An alternative display technique is known as "Centered Averages" which instead positions the Moving Average in the center row of the window. The table following illustrates the difference in these display techniques using the first three values from above:
"Centered Averages" display requires further calculations when the window is an even number and it is not available for Simple Moving Averages and other Moving Functions at this time.
All "Moving Functions" in this particular implementation will display data according to the "Trailing Averages" principle.
Note also that from the above two tables, "Trailing Averages" display causes the initial n-1 (where n = window size) rows of result data to have no value (rows 1 and 2 are blank in the above examples). This is the generally accepted standard for the initial "n-1" terms and is the standard adopted for the implementation of most Moving Functions.
The following table illustrates the above monthly Sales data Simple Moving Average calculation using "Trailing Averages" display:
The Simple Moving Averages of the original range of values for a window of 3 (i.e. in this case, a 3-Month Simple Moving Average) could be evaluated to be: