Skew

Skew is a general term used in science, engineering, and everyday language to describe asymmetry, bias, or deviation from a reference orientation. It can refer to distortion in measurement, misalignment of components, or a systematic tilt away from a standard position.

Statistics and probability use the term skew to describe asymmetry of a distribution. A distribution is said to be skewed if its left and right tails differ in length or weight. A right-skewed (positive skew) distribution has a longer right tail and a concentration of values on the left; a left-skewed (negative skew) distribution has a longer left tail. Skewness is commonly quantified by the third standardized moment, and by Bowley’s measure based on quartiles; negative values indicate left skew, positive values indicate right skew.

Geometrically, skew describes a relation between lines or planes that do not intersect or are not parallel. Skew lines in three-dimensional space do not meet and are not coplanar. Skew can also describe oblique angles or shears in constructions, where alignment is offset.

Linear algebra uses skew-symmetric matrices A, satisfying A^T = -A. Such matrices represent rotations and cross products in physics and engineering; their eigenvalues are purely imaginary or zero.

Data systems encounter data skew when the distribution of values is highly uneven, causing load imbalance in partitioned or parallel processing. Remedies include data repartitioning, hashing adjustments, or sampling.

In typography and graphics, skew refers to a shear transformation that slants shapes or text, producing an oblique appearance without changing shape size.