.. _model-surrogate-non_hierarchical:

""""""""""""""""
non_hierarchical
""""""""""""""""


Non-hierarchical surrogates employ an unordered set of lower-fidelity
models to approximate a truth reference model at reduced cost.


.. toctree::
   :hidden:
   :maxdepth: 1

   model-surrogate-non_hierarchical-truth_model_pointer
   model-surrogate-non_hierarchical-unordered_model_fidelities


**Specification**

- *Alias:* model_ensemble 

- *Arguments:* None


**Child Keywords:**

+-------------------------+--------------------+--------------------------------+---------------------------------------------+
| Required/Optional       | Description of     | Dakota Keyword                 | Dakota Keyword Description                  |
|                         | Group              |                                |                                             |
+=========================+====================+================================+=============================================+
| Required                                     | `truth_model_pointer`__        | Pointer to specify a "truth" model, from    |
|                                              |                                | which to construct a surrogate              |
+----------------------------------------------+--------------------------------+---------------------------------------------+
| Optional                                     | `unordered_model_fidelities`__ | Specification of an unordered ensemble of   |
|                                              |                                | low-fidelity approximations                 |
+----------------------------------------------+--------------------------------+---------------------------------------------+

.. __: model-surrogate-non_hierarchical-truth_model_pointer.html
__ model-surrogate-non_hierarchical-unordered_model_fidelities.html



**Description**