.. _method-multilevel_multifidelity_sampling-solution_mode-online_pilot:

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online_pilot
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Specify a solution mode that includes the pilot cost within the sample allocation logic


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**Specification**

- *Alias:* None

- *Arguments:* None


**Description**


Multilevel / multifidelity sampling methods are adaptive
UQ methods that utilize a pilot sample to estimate an initial set of
correlations or variances, and then augment the pilot with additional
sample increments to optimally allocate resources.  In this mode, the
cost of pilot sampling is treated as online cost and is included within
the optimal sample allocation logic.  This mode is the default.

*Additional Discussion*
It is typically advantageous to start from a smaller pilot sample and
then rely on the adaptive logic to increase the sample levels to the
optimal level required to achieve the desired accuracy or enforce the
prescribed budget.  Over-estimation of the pilot, while supporting more
robust estimation of correlations and variances, can hide the optimal
profile and result in a non-optimal allocation of resources.


