Check.

Quality control (QC) can be simplified into the act of checking output.  A sample of the outputs, nominally known as ‘widgets’ in a manufacturing sense, is taken to check that the output has met the requirements.  There’s a whole industry around quality control (and management), but fundamentally it’s checking the output. 

Knowledge workers are in an interesting position of not being consistently, officially subjected to checking procedures – not like manufacturing plants are anyway, where a statistical sample of outputs are selected for a quality control check.  The knowledge worker output is generally trusted upon receipt, without a statistical sampling check.