Applies a moving n-term median (middle number) to an input data set. Each term in the list is replaced by a trailing median of n terms, and the first terms (the n-1 terms) are copies of the input data. @MOVMED modifies a data set for smoothing purposes.
Syntax
@MOVMED (mbrName [, n [, XrangeList]])
Parameter | Description |
---|---|
mbrName |
Any valid single member name or member combination, or a function that returns a single member or member combination. |
n |
Optional. A positive integer value that represents the number of values that are used to calculate the moving median. The default is 3. |
XrangeList |
Optional. A valid member name, a comma-delimited list of member names, cross dimension members, or a member set function or range function (including @XRANGE) that returns a list of members from the same dimension. If XrangeList is not specified, Essbase uses the level 0 members from the dimension tagged as Time. |
Notes
While calculating the moving median, the @MOVMED function skips #MISSING values. For example, if one value out of four is #MISSING, @MOVMED calculates the median of the remaining three values.
The @MOVMED function calculates a trailing, rather than a centered, median. For example:
Trailing Median Centered Median 1 2 3 1 2 3 2 2
If the group of values being used to calculate the median contains an even number of values, the @MOVMED function averages the two numbers in the middle.
If you use an Essbase member set function to generate a member list for the XrangeList parameter (for example, @SIBLINGS), to ensure correct results, consider the order in which Essbase sorts the generated member list. For more information, see the help topic for the member set function you are using.
When you use @MOVMED in a calculation script, use it within a FIX statement. Although FIX is not required, using it may improve calculation performance.
When you use @MOVMED across a large range in a sparse dimension, you may need to increase the size of the calculator cache. For more information on the calculator cache, see the Oracle Essbase Database Administrator's Guide.
Example
The following example is based on the Sample Basic database. Assume that the Measures dimension contains an additional member, Mov Med.
"Mov Med" = @MOVMED(Sales,3,Jan:Jun);
In this example, the @MOVMED function smooths sales data for the first six months of the year (Jan through Jun). The results of @MOVMED could be used with the @TREND function to forecast sales data for a holiday season (for example, October - December).
This example produces the following report:
Colas New York Actual Sales Mov Med ===== ======= Jan 678 678 Feb 645 645 Mar 675 675 Apr 712 675 May 756 712 Jun 890 756
In this example, Essbase uses three values at a time to calculate the moving median. The first two values (Jan,Feb) for Mov Med are the same as the first two values for Sales. The value for Mar represents the trailing median of Jan, Feb, and Mar. The value for Apr represents the trailing median of Feb, Mar, and Apr. The remaining values represent the trailing median of each group of three values.
See Also