Introduction to Units

How do Units help us build better Models?

When we build models in Excel, we often use units only as an afterthought. Maybe we add a column in which we write a $ symbol to indicate that a line is in US Dollars. But this is only done as a hint to the spreadsheet user and has no direct impact on any calculations.

In Models, Units are built into the fundamental workings of the software. Each Variable has a Unit, and if a Calculation produces an inconsistent Unit, you will see a warning, letting you know that there may be a logical error in your Model.

Units in Models also allow you to automatically move between items of different size, e.g. $ to $000 to $m, (see Factors).

Units also enable much of the advanced functionality in Models, such as:

• Automatically matching Assumptions to Variables.

• Aggregation of multiple Variables

• Performing automatic and custom Dimension references in Calculations

For the most part, you don't have to use Units to produce a working Model. Inconsistent Units will only produce warnings, not errors, and calculations will still be performed. And if you want to, you can create a Model with only Unitless Variables.

The Models UI is designed to make the use of Units as easy as possible, and to add only a small overhead to your build process.

We hope that once you understand how Units work, it will help you build better, more-readable Models, with fewer errors.