Matched

Matched is the past tense and past participle of the verb match. It also functions as an adjective meaning that two or more items correspond, pair, or are suitable for one another. The term appears in everyday usage as well as in specialized technical contexts.

In statistics and research design, matched refers to paired observations or samples that are chosen to be similar on certain confounding variables, to reduce bias. Matched-pairs design and matching methods, including propensity score matching, pair units with similar characteristics to improve causal inference in observational studies.

In graph theory, a matching is a set of edges with no shared endpoints; a vertex is said to be matched if it is incident to a chosen edge. A perfect matching covers all vertices, while a maximum matching has the greatest possible number of edges. These concepts are central to many algorithms and theoretical results in combinatorics.

In electronics, impedance matching is the practice of making the source and load impedances equal or conjugate to optimize power transfer and minimize signal reflections, particularly in transmission lines and RF circuits.

In computer science and linguistics, pattern matching refers to locating strings or structures that satisfy a pattern or rule, often implemented in programming languages and search tools. In sports and gaming, a match is a contest or game, and players or teams described as well matched are of similar ability or strength.