Modifier Drivers
What is a modifier driver
Modifier drivers are series that adjust other drivers or variables. They rarely represent real world quantities by themselves.
Typical forms:
Percentages or multipliers.
Index values that scale a base value.
Scenario factors that tilt another series up or down.
Seasonality factors applied to a base trend.
Examples:
Driver - Modifier - Scenario Scale - RevenueDriver - Seasonality - Retail - Monthly IndexDriver - Discount Factor - Customer IncentivesDriver - Modifier - Cost Saving Programme
These drivers are usually dimensionless or expressed in percentages rather than cash or unit terms.
Modifier drivers vs other drivers
Compared to other drivers:
Economic drivers represent external conditions such as prices, FX or interest rates.
Operational drivers represent internal activity such as units, headcount or utilisation.
Modifier drivers represent the way you adjust other series to represent discounts, uplift, seasonality or scenarios.
Modifiers are layered on top of economic and operational drivers rather than standing alone.
Storing modifier drivers
In the Data Library, name and tag modifier drivers clearly, for example:
Name:
Driver - Seasonality - Subscriptions - MonthlyUnits:
IndexorPercentTags:
Seasonality,Modifier,Scenario
Typical values and meanings:
1.0 for no change.
Above 1.0 for uplift.
Below 1.0 for reductions.
Or percentage values that are applied as gross up or discount rates.
Document in the notes how the modifier should be interpreted in formulas.
## Using modifier drivers in formulas
Examples of how modifiers can be used:
Scenario scale
Formula: {% code title="Scenario scale" %}
Revenue = BaseRevenue * ScenarioScale{% endcode %}
Where
ScenarioScaleis greater than 1 in upside scenarios and less than 1 in downside cases.
Seasonality
Formula: {% code title="Seasonality" %}
Revenue = BaseTrend * SeasonalityIndex{% endcode %}
SeasonalityIndexrepresents relative strength within a year while preserving the annual total.
Discounts and promotions
Formulas: {% code title="Discounts and promotions" %}
NetPrice = ListPrice * (1 - DiscountRate) COGS = BaseCOGS * CostReductionIndex{% endcode %}
Modifiers let you express these relationships without changing the underlying economics or operations drivers directly.
Scenario design with modifiers
Modifier drivers are particularly useful for scenarios because:
You can keep base economic and operational drivers stable.
You overlay scenario effects using modifiers.
Modifiers can be toggled or edited without needing to touch core series.
Examples:
Driver - Modifier - Downside - Revenuethat gradually reduces revenue relative to base.Driver - Modifier - Cost Saving Planthat reduces certain Opex categories in transformation scenarios.Driver - Modifier - Capex Deferralthat shifts some investments later in the horizon.
This keeps scenario logic explicit and easy to compare.
Good practice for modifier drivers
Guidelines:
Make modifier names very clear about their purpose and scope.
Keep base drivers and modifiers separate so you can see both the underlying plan and the adjustments.
Use values of 1.0 as the neutral baseline when using multiplicative modifiers.
Document how modifiers are applied, especially if multiple modifiers stack on the same variable.
Transparent modifiers make scenario conversations much easier with non modellers.
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