Custom field gives different values depending on the order injections are processed - WKB204968

SYMPTOMS

• Across 10 results, there is a varying split between two values
• The split changes depending on if the injections are processed 1 through 10 or 10 through 1
• Custom field: ROUND(SAME.%..AVE(ROUND(CU_pcnt,-1)),-1)

ENVIRONMENT

• Empower
• Results
• Custom field
• Report Publisher

CAUSE

The ROUND function was embedded in the AVE function.

FIX or WORKAROUND

1. Do not embed the ROUND function in other functions in custom fields.
2. Do not use the ROUND function to calculate intermediate values for use in other calculations.
3. Rewrite this summary custom field AV_mean; ROUND(SAME.%..AVE(ROUND(CU_pcnt,-1)),-1) as ROUND(SAME.%..AVE(CU_pcnt),-1).

ADDITIONAL INFORMATION

The Round function was implemented to allow a user to compare numbers at a specified precision. It was not designed to calculate a value that is then used as an intermediate value in another calculation.

Note that the loss of precision due to the Round function ensures that the sum and mean of the rounded numbers are different than the sum and mean of the unrounded numbers. 

Users cannot expect to get the most accurate result from a custom field calculation that is based on a rounded value. Use of the Round function in a custom field formula causes the calculated number to lose precision (significant figures). The resulting value is a different number that is less accurate than the original value due to this loss of precision.

See - WKB199470, TECN134632666, and TECN1851937