MOVINGAVERAGE

The MOVINGAVERAGE function (abbreviated MVAVG) computes a series of averages for the values of a dimensioned variable or expression over a specified dimension. For each dimension value in status, MOVINGAVERAGE computes the average of the data in the range specified, relative to the current dimension value.

When the data being averaged has only one dimension, MOVINGAVERAGE produces a single series of averages, one for each dimension value in status. When the data has dimensions other than the one being averaged over, MOVINGAVERAGE produces a separate series of averages for each combination of values in the status list of the other dimensions.

Return Value

DECIMAL

Syntax

MOVINGAVERAGE(expression, start, stop, step, -

[dimension [STATUS|limit-clause]])

Arguments

expression

A numeric variable or calculation whose values you want to average; for example, units or sales-expense.

start

A whole number that specifies the starting point of the range over which you want to average. The range is specified relative to the current value of dimension. Zero (0) refers to the current value, and -1 refers to the value preceding the current value. A comma is required before a negative start number.

Each average is based on data for a specified range of dimension values preceding, including, or following the one for which the average is being calculated. To count the values in the range, MOVINGAVERAGE uses the default status, unless you use the STATUS keyword or the limit-clause argument to specify a different dimension status.

stop

A whole number that specifies the ending point of the range over which you want to average. A negative stop number must be preceded by a comma.

step

A positive whole number that specifies whether to average over every value in the range, every other value, every third value, and so on. A value of 1 for step means average over every value. A value of 2 means average over the first value, the third value, the fifth value, and so on. For example, when the current month is Jun96 and the start and stop values are -3 and 3, a step value of 2 means average over Mar96, May96, Jul96, and Sep96.

dimension

The dimension over which the moving average is calculated. While this can be any dimension, it is typically a hierarchical time dimension of type TEXT that is limited to a single level (for example, the month or year level) or a dimension with a type of DAY, WEEK, MONTH, QUARTER, or YEAR.

When expression has a dimension with a type of DAY, WEEK, MONTH, QUARTER, or YEAR and you want MOVINGAVERAGE to use that dimension, you can omit the dimension argument.

STATUS

Specifies that MOVINGAVERAGE should use the current status list (that is, only the dimension values currently in status in their current status order) when calculating the moving average.

limit-clause

Specifies that MOVINGAVERAGE should use the default status limited by limit-clause when calculating the moving average.

The syntax of limit-clause is the same syntax as any of the limit-clause arguments in the various forms of the LIMIT command (that is, the syntax of the LIMIT command after the limit-type argument such as "TO"). For the syntax of these arguments, see LIMIT (using values) command, LIMIT using LEVELREL command, LIMIT command (using parent relation), LIMIT (using related dimension) command, LIMIT NOCONVERT command, and LIMIT command (using POSLIST).

To specify that MOVINGAVERAGE should use the current status limited by limit-clause when calculating, specify a LIMIT function for limit-clause.

Examples

Example 8-31 Calculating a Moving Average

Suppose you have a variable called sales that is dimensioned by a hierarchical dimension named time, a dimension named product, a dimension named timelevelnames that contains the names of the levels of time (for example, Quarter and Year), and a relation named time.levelrels that relates the values of time to the values of timelevelnames. Assume also that using the following statements you limit product to Womens - Trousers and time to quarters from Q4-1999 to present.

LIMIT product TO 'Womens - Trousers'
LIMIT timelevelnames TO 'Quarter'
LIMIT time TO time.levelrels
LIMIT time REMOVE 'Q1-1999' 'Q2-1999' 'Q3-1999'

After you have limited product and sales, you issue the following report statement.

REPORT DOWN time sales -
HEADING 'Running Yearly\nTotal' MOVINGTOTAL(sales, -4, 0, 1, time, -
     LEVELREL time.levelrels) -
HEADING 'Minimum\nQuarter' MOVINGMIN(sales, -4, 0, 1, time, -
     LEVELREL time.levelrels) -
HEADING 'Maximum\nQuarter' MOVINGMAX(sales, -4, 0, 1, time, -
     LEVELREL time.levelrels) -
HEADING 'Average\nQuarter' MOVINGAVERAGE(sales, -4, 0, 1, time, -
     LEVELREL time.levelrels)

The following report was created by the preceding statement.

-----------------------PRODUCT------------------------
               ------------------Womens - Trousers-------------------
                          Running
                          Yearly     Minimum    Maximum    Average
TIME           SALES      Total      Quarter    Quarter    Quarter
-------------- ---------- ---------- ---------- ---------- ----------
Q4-1999         416            1,386        233        480     346.50
Q1-2000         465            1,851        233        480     370.20
Q2-2000         351            1,969        257        480     393.80
Q3-2000         403            2,115        351        480     423.00
Q4-2000         281            1,916        281        465     383.20
Q1-2001         419            1,919        281        465     383.80
Q2-2001         349            1,803        281        419     360.60
Q3-2001         467            1,919        281        467     383.80
Q4-2001         484            2,000        281        484     400.00
Q1-2002         362            2,081        349        484     416.20
Q2-2002         237            1,899        237        484     379.80
Q3-2002         497            2,047        237        497     409.40
Q4-2002         390            1,970        237        497     394.00