# Selecting Driver Type

This article explains how to **select the right driver type** in Model Reef.

You will learn:

* What driver types exist.
* How each type is intended to be used.
* How driver type affects where the driver appears and how it is referenced.

Drivers do not hit financial statements directly. They are reusable input series that variables and formulas reference.

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### Driver types in Model Reef

Model Reef supports three main driver classes:

* **Economic drivers**\
  Prices, inflation, FX rates, index series and other value based or market based assumptions.
* **Operational drivers**\
  Units, volumes, headcount, hours, utilisation and other activity based assumptions.
* **Modifier drivers**\
  Growth rates, uplift factors, seasonal indices, discount factors and other pure multipliers or scalars.

All three types are stored as time series and can be used anywhere drivers are allowed.
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### Where to choose driver type

You choose driver type when you:

* Create a new driver in the **Driver Editor**.
* Convert or reclassify a Data Library entry as a driver.
* Map imported series from external sources that you intend to use as drivers.

The driver type is shown alongside the driver name for easy identification.
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### How driver type affects usage

Driver type influences:

* How you think about the meaning of the driver (price, quantity or pure modifier).
* Where it is likely to be used in formulas.
* How other team members interpret it when they see it in sidebars and pickers.

It does not directly change accounting behaviour, but it is important for model clarity and governance.
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### Choosing the right type

As a rule of thumb:

* Use **economic drivers** for anything that behaves like a monetary rate, price, index or macro series.
* Use **operational drivers** for quantities, counts and utilisation measures.
* Use **modifier drivers** for relative adjustments, growth rates and percentages that modify other series.

Choose a type that matches how the driver will be used most of the time.
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### Reclassifying driver type

You can change a driver type later if needed:

* Reclassification does not change the underlying time series.
* All variables and formulas referencing the driver continue to work.
* The driver will appear under the new type grouping in the Driver Editor and sidebars.

Document any major reclassifications with notes so collaborators understand what changed.
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***

## Related articles

* [Driver Editor Screen](/syntax/understanding-the-interface/driver-editor-screen.md)
* [Economic Driver Fields](/syntax/drivers-syntax/economic-driver-fields.md)
* [Driver Escalation Rules](/help/drivers-variables-and-timing/driver-escalation-rules.md)
* [Build a Recurring Revenue Forecast](/how-tos/core-modelling/build-a-recurring-revenue-forecast.md)


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