.. _method-approximate_control_variate-solver_metric:

"""""""""""""
solver_metric
"""""""""""""


Metric employed during numerical solutions in sampling-based multifidelity UQ methods.



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

   method-approximate_control_variate-solver_metric-average_estimator_variance
   method-approximate_control_variate-solver_metric-norm_estimator_variance
   method-approximate_control_variate-solver_metric-max_estimator_variance


**Specification**

- *Alias:* None

- *Arguments:* None

- *Default:* average_estimator_variance


**Child Keywords:**

+-------------------------+--------------------+--------------------------------+-----------------------------------------------+
| Required/Optional       | Description of     | Dakota Keyword                 | Dakota Keyword Description                    |
|                         | Group              |                                |                                               |
+=========================+====================+================================+===============================================+
| Required (Choose One)   | Optimization       | `average_estimator_variance`__ | Utilize the estimator variance averaged over  |
|                         | Solver Metric      |                                | the QoI as the solver metric for              |
|                         |                    |                                | sampling-based multifidelity methods.         |
|                         |                    +--------------------------------+-----------------------------------------------+
|                         |                    | `norm_estimator_variance`__    | Utilize a p-norm over the vector of QoI       |
|                         |                    |                                | estimator variances as the solver metric for  |
|                         |                    |                                | sampling-based multifidelity methods.         |
|                         |                    +--------------------------------+-----------------------------------------------+
|                         |                    | `max_estimator_variance`__     | Utilize the maximum estimator variance as the |
|                         |                    |                                | solver metric for sampling-based              |
|                         |                    |                                | multifidelity methods.                        |
+-------------------------+--------------------+--------------------------------+-----------------------------------------------+

.. __: method-approximate_control_variate-solver_metric-average_estimator_variance.html
__ method-approximate_control_variate-solver_metric-norm_estimator_variance.html
__ method-approximate_control_variate-solver_metric-max_estimator_variance.html



**Description**


For sampling-based multifidelity UQ methods, this specification
selects the metric to be used during numerical solutions for sample
allocations per model.  When there are multiple quantities of interest
(QoI), the vector of QoI estimator variances needs to be converted to
a scalar for use by the numerical solver.  Options include the
average, maximum, and p-norm of the QoI vector, with the default of
average estimator variance.




**Examples**



.. code-block::

    method,
	approximate_control_variate acv_mf
	  solver_metric norm_estimator_variance norm_order = 2	# objective fn for budget-constrained
	solution_mode  online_pilot
	pilot_samples = 50 seed = 8674132
	max_function_evaluations = 500