Abweichung

Abweichung is a German term meaning deviation or departure. It denotes how far a value or result differs from a reference value, a norm, or an expected result. In common usage, Abweichung refers to the magnitude and sometimes the direction of the departure from what is considered standard.

In statistics and data analysis, Abweichung describes the difference between an observed value x and a reference value x0: d = x − x0. The size of the deviation is often expressed as the absolute deviation |d|, or as a relative deviation [(x − x0)/x0] × 100%. The term is related to, but distinct from, dispersion measures such as the standard deviation, which quantify variability across a data set rather than the difference of a single observation from a reference point. In regression analysis, residuals are a form of Abweichung.

In metrology, quality control and manufacturing, Abweichung specifies how far a measured or produced item deviates from its nominal value or tolerance interval. Tolerances define allowable Abweichungen; values outside the tolerance are rejected or require adjustment. The Abweichung can be systematic (bias) or random (measurement noise), and separating these sources is important for calibration and process improvement.

Wegabweichung and Abweichung from a target path or geometry are common phrases in engineering. Abweichung is a neutral, widely used term across disciplines to describe any departure from a reference standard, whether in numbers, dimensions, or behavior.