BrandTech Scientific EASYCAL 4.0 - Manual (Page 25)

EASYCAL ™ User Guide Version 4.0 · Status: June 2008 25
EASYCAL
™
User Guide
Poor accuracy:
Hits far off center.
Poor reproducibility:
Hits widely scattered.
Result:
These volumetric instruments are of inferior quality.
Good accuracy:
On average, hits are evenly distributed around center.
Poor reproducibility:
No gross errors, but hits widely scattered.
Result:
All deviations are “equally” probable. Instruments exceeding the
permissible limit should be removed from service.
Poor accuracy:
Although all hits are close together, the center (true volume) is still
missed.
Good reproducibility:
All hits are close together.
Result:
Systematicerror.Instruments exceeding the permissible limit should
be removed from service.
Good accuracy:
All hits are near the center, i.e., the specified value.
Good reproducibility:
All hits are close together.
Result:
The volumetric instruments have minute systematic errors, narrow
scatter; the permissible limit is not exhausted. These instruments
should remain in service.
The illustrations demonstrate the concepts of accuracy and precision. The center of the target represents the
specified value, and each hit on the target represents volumes actually measured by the instrument. There
are four possible outcomes.