RUNNING_AVE: Calculating an Average Over a Group of Rows

How to:

Calculate Running Average Between the Current and a Prior Value of a Field

Given an aggregated input field and a negative offset, RUNNING_AVE calculates the average of the values between the current row of the report output and one or more prior rows, within a sort break or the entire table. The reset point for the calculation is determined by the sort field specified, the entire table, or the value of the PARTITION_ON parameter described in Specify the Partition Size for Simplified Statistical Functions.

Syntax: How to Calculate Running Average Between the Current and a Prior Value of a Field

RUNNING_AVE(field, reset_key, lower)

where:

field

Numeric

The field to be used in the calculation.

reset_key

Identifies the point at which the running average restarts. Valid values are:

The name of a sort field in the request.
PRESET, which uses the value of the PARTITION_ON parameter, as described in Specify the Partition Size for Simplified Statistical Functions.
TABLE, which indicates that there is no break on a sort field.

Note: The values used in the calculations depend on the sort sequence (ascending or descending) specified in the request. Be aware that displaying a date or time dimension in descending order may produce different results than those you may expect.

lower

Is the starting point in the partition for the running average. Valid values are:

A negative number, which identifies the offset from the current row.
B, which specifies the beginning of the sort group.

Example: Calculating a Running Average

The following request calculates a running average of QUANTITY_SOLD within the PRODUCT_CATEGORY sort field, always starting from the beginning of the sort break.

TABLE FILE wflite
SUM QUANTITY_SOLD
COMPUTE RAVE = RUNNING_AVE(QUANTITY_SOLD,PRODUCT_CATEGORY,B);
BY PRODUCT_CATEGORY
BY PRODUCT_SUBCATEG
ON TABLE SET PAGE NOLEAD
ON TABLE SET STYLE *
GRID=OFF,$
ENDSTYLE
END

The output is shown in the following image. The first value for RAVE is the value in the Accessories category for Quantity Sold, as there is no prior value. The second value for RAVE is the average of the values for Headphones and Charger, the third is the average of the values for Headphones, Charger, and Universal Remote Controls. Then, the calculations start over for Camcorder, which is the reset point.