.. _method-multilevel_blue-group_throttle:

""""""""""""""
group_throttle
""""""""""""""


Reduce the number of groups in multilevel BLUE using a throttle



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

   method-multilevel_blue-group_throttle-mfmc_groups
   method-multilevel_blue-group_throttle-common_groups
   method-multilevel_blue-group_throttle-group_size
   method-multilevel_blue-group_throttle-best_conditioned
   method-multilevel_blue-group_throttle-rcond_tolerance


**Specification**

- *Alias:* None

- *Arguments:* None


**Child Keywords:**

+-------------------------+--------------------+----------------------+-----------------------------------------------+
| Required/Optional       | Description of     | Dakota Keyword       | Dakota Keyword Description                    |
|                         | Group              |                      |                                               |
+=========================+====================+======================+===============================================+
| Required (Choose One)   | Throttle Approach  | `mfmc_groups`__      | Throttle multilevel BLUE to only search over  |
|                         |                    |                      | MFMC groups                                   |
|                         |                    +----------------------+-----------------------------------------------+
|                         |                    | `common_groups`__    | Throttle multilevel BLUE to only search over  |
|                         |                    |                      | common groups                                 |
|                         |                    +----------------------+-----------------------------------------------+
|                         |                    | `group_size`__       | Throttle multilevel BLUE to only search over  |
|                         |                    |                      | groups of a maximum size                      |
|                         |                    +----------------------+-----------------------------------------------+
|                         |                    | `best_conditioned`__ | Throttle multilevel BLUE to only solve for    |
|                         |                    |                      | allocations using the groups with the best    |
|                         |                    |                      | conditioning in their group covariances       |
|                         |                    +----------------------+-----------------------------------------------+
|                         |                    | `rcond_tolerance`__  | Throttle multilevel BLUE to only solve for    |
|                         |                    |                      | allocations using groups with prescribed      |
|                         |                    |                      | conditioning in their group covariances       |
+-------------------------+--------------------+----------------------+-----------------------------------------------+

.. __: method-multilevel_blue-group_throttle-mfmc_groups.html
__ method-multilevel_blue-group_throttle-common_groups.html
__ method-multilevel_blue-group_throttle-group_size.html
__ method-multilevel_blue-group_throttle-best_conditioned.html
__ method-multilevel_blue-group_throttle-rcond_tolerance.html



**Description**


The number of groups in ML BLUE is, by default, determined by all
combinations of the model indices, spanning the truth model and all
approximations.  This combinatorial growth quickly results in very
large group counts as the number of model approximations grows.  This
number of combinations may be optionally throttled using one of the
following schemes: ``mfmc_groups``, ``common_groups``, ``group_size``,
``best_conditioned``, or ``rcond_tolerance``.

*Default Behavior*

The default is no throttle: all model combinations are included.