Estimater

Estimater is a noun that is occasionally used to denote a person who makes estimates. In modern English, however, the preferred form is estimator, and estimater is generally considered a misspelling or archaic variant. The term can refer to a professional who forecasts quantities, costs, or resources in fields such as construction, engineering, or project management; titles include cost estimator or quantity estimator.

In statistics and data analysis, an estimator is a rule or algorithm that yields an estimate of an unknown population parameter from sample data. The value produced by applying the estimator to data is called the estimate. This mathematical usage is central to estimation theory, where properties such as bias, variance, and efficiency are studied to assess how well an estimator performs.

Spelling and usage notes: estimater may appear in older texts or in non-native contexts, but most dictionaries mark it as uncommon or incorrect in standard usage. When referring to the person who performs estimation, estimator is the correct form in contemporary writing; when referring to the statistical concept, estimator is also the correct term.

See also: estimator, estimation, statistical estimator, cost estimator, estimation theory.