Metrology is the science of measurement and encompasses all theoretical and practical aspects of measurement. A core concept in metrology is metrological traceability, which establishes the comparability of measurements through an unbroken chain of calibrations to national or international standards with stated uncertainties. Traceability is obtained through calibration of measuring instruments to measurement standards coordinated by national metrological institutes. Traceability allows extending measurements across different measurement methods and regimes and is critical for quality management systems by relating measurements to primary standards with evaluations of accuracy, precision, bias, and uncertainty.

1. Metrology (What it is, What it encompasses, how it relates to Quality, what it requires, etc.).
Solution
Metrology is the science of measurement. Metrology includes all theoretical and practical
aspects of measurement. The word comes from Greek ?????? (metron), "measure"+ "?????"
(logos), amongst others meaning "speech, oration, discourse, quote, study, calculation, reason".
In Ancient Greek the term ?????????? (metrologia) meant "theory of ratios"
A core concept in metrology is metrological traceability, defined by the BIPM as "the property
of the result of a measurement or the value of a standard whereby it can be related to stated
references, usually national or international standards, through an unbroken chain of
comparisons, all having stated uncertainties." The level of traceability establishes the level of
comparability of the measurement: whether the result of a measurement can be compared to the
previous one, a measurement result a year ago, or to the result of a measurement performed
anywhere else in the world.
Traceability is most often obtained by calibration, establishing the relation between the
indication of a measuring instrument and the value of a measurement standard. These standards
are usually coordinated by national metrological institutes: National Institute of Standards and
Technology, National Physical Laboratory, UK, Physikalisch-Technische Bundesanstalt, etc.
Traceability is used to extend measurement from a method that works in one regime to a
different method that works in a different regime, by calibrating the two using an overlapping
range where both work. An example would be the measurement of the spacing of atomic planes
in the same crystal specimen using both X-rays and an electron beam. Traceability also refers to
the methodology used to calibrate various instruments by relating them back to a primary
standard.
Traceability, accuracy, precision, systematic bias, evaluation of measurement uncertainty are
critical parts of a quality management system.