.. _method-surrogate_based_uq:

""""""""""""""""""
surrogate_based_uq
""""""""""""""""""


Generic UQ method for constructing and interrogating a surrogate model.


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

   method-surrogate_based_uq-samples_on_emulator
   method-surrogate_based_uq-sample_type
   method-surrogate_based_uq-rng
   method-surrogate_based_uq-probability_refinement
   method-surrogate_based_uq-final_moments
   method-surrogate_based_uq-response_levels
   method-surrogate_based_uq-probability_levels
   method-surrogate_based_uq-reliability_levels
   method-surrogate_based_uq-gen_reliability_levels
   method-surrogate_based_uq-distribution
   method-surrogate_based_uq-variance_based_decomp
   method-surrogate_based_uq-diagonal_covariance
   method-surrogate_based_uq-full_covariance
   method-surrogate_based_uq-import_approx_points_file
   method-surrogate_based_uq-export_approx_points_file
   method-surrogate_based_uq-seed
   method-surrogate_based_uq-fixed_seed
   method-surrogate_based_uq-model_pointer


**Specification**

- *Alias:* None

- *Arguments:* None


**Child Keywords:**

+-------------------------+--------------------+-------------------------------+-----------------------------------------------+
| Required/Optional       | Description of     | Dakota Keyword                | Dakota Keyword Description                    |
|                         | Group              |                               |                                               |
+=========================+====================+===============================+===============================================+
| Optional                                     | `samples_on_emulator`__       | Number of samples at which to evaluate an     |
|                                              |                               | emulator (surrogate)                          |
+----------------------------------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `sample_type`__               | Selection of sampling strategy                |
+----------------------------------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `rng`__                       | Selection of a random number generator        |
+----------------------------------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `probability_refinement`__    | Allow refinement of probability and           |
|                                              |                               | generalized reliability results using         |
|                                              |                               | importance sampling                           |
+----------------------------------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `final_moments`__             | Output moments of the specified type and      |
|                                              |                               | include them within the set of final          |
|                                              |                               | statistics.                                   |
+----------------------------------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `response_levels`__           | Values at which to estimate desired           |
|                                              |                               | statistics for each response                  |
+----------------------------------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `probability_levels`__        | Specify probability levels at which to        |
|                                              |                               | estimate the corresponding response value     |
+----------------------------------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `reliability_levels`__        | Specify reliability levels at which the       |
|                                              |                               | response values will be estimated             |
+----------------------------------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `gen_reliability_levels`__    | Specify generalized relability levels at      |
|                                              |                               | which to estimate the corresponding response  |
|                                              |                               | value                                         |
+----------------------------------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `distribution`__              | Selection of cumulative or complementary      |
|                                              |                               | cumulative functions                          |
+----------------------------------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `variance_based_decomp`__     | Activates global sensitivity analysis based   |
|                                              |                               | on decomposition of response variance into    |
|                                              |                               | main, interaction, and total effects          |
+-------------------------+--------------------+-------------------------------+-----------------------------------------------+
| Optional (Choose One)   | Covariance Type    | `diagonal_covariance`__       | Display only the diagonal terms of the        |
|                         |                    |                               | covariance matrix                             |
|                         |                    +-------------------------------+-----------------------------------------------+
|                         |                    | `full_covariance`__           | Display the full covariance matrix            |
+-------------------------+--------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `import_approx_points_file`__ | Filename for points at which to evaluate the  |
|                                              |                               | PCE/SC surrogate                              |
+----------------------------------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `export_approx_points_file`__ | Output file for surrogate model value         |
|                                              |                               | evaluations                                   |
+----------------------------------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `seed`__                      | Seed of the random number generator           |
+----------------------------------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `fixed_seed`__                | Reuses the same seed value for multiple       |
|                                              |                               | random sampling sets                          |
+----------------------------------------------+-------------------------------+-----------------------------------------------+
| Optional                                     | `model_pointer`__             | Identifier for model block to be used by a    |
|                                              |                               | method                                        |
+----------------------------------------------+-------------------------------+-----------------------------------------------+

.. __: method-surrogate_based_uq-samples_on_emulator.html
__ method-surrogate_based_uq-sample_type.html
__ method-surrogate_based_uq-rng.html
__ method-surrogate_based_uq-probability_refinement.html
__ method-surrogate_based_uq-final_moments.html
__ method-surrogate_based_uq-response_levels.html
__ method-surrogate_based_uq-probability_levels.html
__ method-surrogate_based_uq-reliability_levels.html
__ method-surrogate_based_uq-gen_reliability_levels.html
__ method-surrogate_based_uq-distribution.html
__ method-surrogate_based_uq-variance_based_decomp.html
__ method-surrogate_based_uq-diagonal_covariance.html
__ method-surrogate_based_uq-full_covariance.html
__ method-surrogate_based_uq-import_approx_points_file.html
__ method-surrogate_based_uq-export_approx_points_file.html
__ method-surrogate_based_uq-seed.html
__ method-surrogate_based_uq-fixed_seed.html
__ method-surrogate_based_uq-model_pointer.html



**Description**


As surrogate models by stochastic expansion migrate into the model specification,
this method provides a general-purpose UQ method to interrogate the surrogate for
generating statistics.

This method must identify the surrogate of interest through its ``model_pointer``,
distinguishing it from fully-integrated method specifications such as
:dakkw:`method-polynomial_chaos`, :dakkw:`method-stoch_collocation`, and
:dakkw:`method-function_train` that couple directly with a simulation model
(and form the PCE, SC, FT surrogate approximations implicitly prior to using
them for generating statistics).


