Shrinkage

Shrinkage is the reduction in size, volume, or extent of something. The term is used across disciplines to describe physical changes during processing, aging, or environmental exposure, as well as statistical methods that improve estimation by constraining values toward a central tendency.

In materials science and construction, shrinkage refers to dimensional changes that occur as materials cure, dry, or cool. Concrete shrinks as moisture leaves pores, causing length reduction and possible cracking. Polymers contract when cooled from a melted state. Wood and other natural materials change size with shifts in moisture content, leading to warping if uneven.

In textiles, fabric shrinkage occurs after laundering, depending on fiber type, weave, and finishes. Pre-shrinking processes, such as sanforization, are used to minimize future shrinkage in apparel.

In business and retail, shrinkage denotes the loss of inventory from recorded quantities, arising from theft, administrative errors, damage, or supplier fraud. It is measured as the difference between book inventory and physical stock and is a factor in cost management, often addressed with audits and improved controls.

In statistics and data analysis, shrinkage refers to techniques that reduce estimator variance by pulling estimates toward a central value. Examples include ridge regression and the James-Stein estimator, which can lower overall error at the cost of introducing bias. The concept is also used in Bayesian shrinkage priors and model averaging.