Refining Avogadro’s number on way to new kilo.

Now, a team led by metrologists from Italy’s national institute for metrological research (INRIM) has carried out detailed statistical analyses of the two sets of measurements to arrive at an ‘averaged’ result. Provided that we estimate their correlation – that is, how big or small is the chance that we made the same error in both measurements – we can “average” them, by taking the correlation value into account when averaging, to extract a “neutral” and a bit more accurate value, says INRIM team member Carlo Sasso. This yielded a value for Avogadro’s number of 6.02214082(11)×1023 (the number in parentheses represents the uncertainty of the last digit in the result), with a relative uncertainty of 1.8×10-8.