Variables & linked models
Instead of a single model with all of your variables and formulas, you can structure your work into separate, smaller models, and import variables between them.
There are a few benefits to working with smaller, linked models:
  1. 1.
    There'll be less scrolling around and less potential for confusion for you as you build out your models.
  2. 2.
    It'll be easier for your team to work with separate models. For example, your HR team can work on your Headcount Plan without worrying about your Revenue model.
  3. 3.
    You can have different permissions for each model. For example you may want each department head to access the company's P&L model, without being able to see the underlying salary data for each employee (this will live in a separate Headcount model).
Once you link models together, you can reference variables in linked models in your formulas, and you can import variables and visuals from one into another.
You can think of a model in Causal kind of like a tab in a spreadsheet, and the group of linked models as an entire spreadsheet/workbook. The key difference is that you can set different permissions on each model, despite them being linked
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Linking models

Click on the Models button in the toolbar to open the Models dropdown. This is the main area for housekeeping related to linked models.
  1. 1.
    Click the Link New Model button.
  2. 2.
    Select the model/s you want to link to.
  3. 3.
    The model will now appear in the "Linked Models" section of the Models dropdown
You only need to link a model once — if you want to reference or import multiple variables from the same model, you can do this via a single link.
If you have a model (or group of linked models) open, and you hit the + to create a new model, that new model will automatically be linked to the model you were originally in.

Referencing linked model variables

Once you've linked models, you can easily refer to any of the variables in that linked model when you're writing a formula, just by typing its name. The only difference is that it will show up as a blue variable within a formula (see variable types), and if you hover over the variable you will see which model it is coming from (and Cmd/Ctrl+Click will open the model).
If your linked model variable is broken down by a category that isn't in your current model, and you want to see the breakdown, you'll have to link that category to the current model. See Linking existing categories to models. If you don't link the category to the model, the variable will just display on an aggregated basis (with no category items).
If you reference a linked variable whose model has a different start/end date than the model you're in, any missing values will populate with the empty value setting.

Importing a variable

If you wish to bring in the entire variable from a linked model, within your current model, you can import the variable. This will allow you to see the values of the imported variable across time, alongside the rest of the variables in the current model.
Click on the Models button in the toolbar to open the Models dropdown. This is the main area for housekeeping related to linked models.
  1. 1.
    Select the model you want to import from.
  2. 2.
    You'll see a list of variables that you can import from the other model. Select a variable to import it.
  3. 3.
    It will now show up in the spreadsheet below as a variable, and will be differentiated by its blue label/name.

Using an imported variable

Once you've imported a variable, you can broadly use it like any other variable in your model. You can use it in formulas, and you can add it to Visuals.
The main restriction is that you can't directly modify an imported variable's attributes, except for its name and description. This variable gets the rest of its attributes from the model in which it "lives".
If you want to make changes to an imported variable, double-click on the variable's arrow icon in the spreadsheet to "zoom in" to its model, and make the changes in the original model.