estimaattoria

Estimaattori is a statistical concept referring to a rule or function that produces an estimate of an unknown population parameter from sample data. In Finnish usage, the noun is estimaattori, with inflected forms such as estetm attributed to grammatical cases; the partitive singular form is estimaattoria, which appears in phrases like "käytetään estimaattoria." An estimator’s output is a point estimate, a single number used as an educated guess of the parameter.

In statistics, estimators are central to inference. They are data-driven rules that map observed samples to estimates of quantities such as means, proportions, variances, or model parameters. Common examples include the sample mean as an estimator of the population mean, the sample proportion as an estimator of a population proportion, and the sample variance as an estimator of the population variance. In regression analysis, the least squares estimator computes estimates of regression coefficients, while maximum likelihood estimators are obtained by maximizing the likelihood function for a chosen model.

Estimators have theoretical properties that describe their quality. Unbiased estimators have expected value equal to the parameter; consistent estimators converge to the true parameter as sample size grows; efficient estimators have, under certain conditions, the smallest possible variance among unbiased estimators. The choice of estimator affects confidence intervals, hypothesis tests, and predictive accuracy in applications.

See also: Estimation, Parameter, Statistical inference.