Combined Growth Pattern

The ROLLFORWARD calculates growth individually per driver, so, for example if you have 2% Inflation and 10 % percent growth it will add exactly 12% to the base value. If you instead want to define, that these effects are already influencing each other in the respective year, you can use this pattern.

To illustrate the difference, consider the following comparison:


2018 2019 2020
Base Value 100

Inflation
2% 3%
Growth
10% 11%
ROLLFORWARD('Base Value','Inflation,'Growth')
=100 + (100 * 0.02) + (100 * 0.1) = 112 =112 + (112 * 0.03) + (112 * 0.11) = 127.68
ROLLFORWARD('Base Value','Combined Growth')
= 100 * 1.02 * 1.1 = 112.2 = 112.2 * 1.03 * 1.11 = 128.27

To build models with the combined growth, use the following formula in a separate node.

Combined Growth =

ADDEACH(
   IF(IS_NA('Inflation'), 1.0 , ADDEACH('Inflation',1))
*  IF(IS_NA('Growth'), 1.0 , ADDEACH('Growth',1))
* (More Influencers)
,-1)

(warning) The 'Combined Growth' node must use the unit 'Percent'

And then use this helper node in the ROLLFORWARD function:

ROLLFORWARD('Base Value','Combined Growth')

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