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Model Comparison

Causal models evolve. You might train a Digital Twin on January data, then retrain on February data. Or experiment with different configurations — omitting certain variables, adding domain knowledge, changing temporal settings.

Model Comparison lets you put two Digital Twin versions side by side and understand exactly what changed: which relationships appeared, disappeared, or reversed direction, and how the underlying probability distributions shifted.

This is essential for model governance. Before promoting a new model version, you need evidence of how it differs from the current one.


Accessing Model Comparison

Model Comparison is its own page, not a tab on the twin: the Compare page under the Digital Twins section of your workspace (at …/twins/compare). The twin and version selectors are in the upper right corner.


Selecting models

The comparison tool lets you compare any two Digital Twin versions — including versions from different twins.

Common scenarios:

  • Same twin, different versions — track how the model evolved over retraining

  • Same data, different configurations — compare the effect of constraints or excluded variables

  • Different time periods — see how causal relationships changed between datasets


Comparing twins

Once two models are selected, the comparison view shows both causal graphs side by side with structural differences highlighted.

The Compare page in Separate view: the v1.1.0 and v1.0.0 graphs with a Comparison Overview panel reporting 19 variables in each, 32 vs 31 relationships, 28 common edges, and evaluations of 71.7% vs 69.6%
Two versions compared in the Separate view. The Comparison Overview reports size, structural overlap, and evaluation for both models — here v1.1.0 carries 32 relationships to v1.0.0's 31, sharing 28 edges.

Switching to Diff merges both graphs into a single view, color-coding the edges unique to either model and any whose direction changed. The Comparison Overview panel summarizes the structural overlap, evaluation, equations, and parameters, with Details links into a full breakdown of each.

The Compare page in Diff view: a merged graph with a legend for Model 1 Only, Model 2 Only, Both Models, and Direction Changed, with a handful of coloured unique edges among the shared grey ones
The merged diff view. The 28 shared edges render grey; the coloured edges are unique to one model or flipped direction between them — exactly the differences re-discovery introduced.

Interpreting differences

Structural changes

  • New edges — the model found a relationship not present before; may reflect new patterns in updated data

  • Removed edges — a previously discovered relationship is no longer supported; may indicate data drift

  • Direction changes — causality now flows the opposite way; investigate why

Parameter changes

Even when structure is identical, parameters can differ. The conditional influence between variables may have become stronger, weaker, or changed in functional form.

Questions to ask

  1. Are structural changes expected given the data differences?

  2. Do direction changes make domain sense?

  3. Would these changes affect downstream decisions?


Creating a second twin to compare

To compare two configurations or time periods, create a second Digital Twin from the same (or a different) Data View. Both twins will then be available in the Compare page selectors.

For Digital Twin creation steps, see Build Digital Twin.

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