Ühemuutuja

Ühemuutuja is an Estonian term meaning a single variable or univariate quantity, used in mathematics, statistics and related fields to describe objects that depend on exactly one independent variable. In mathematics a ühemuutuja function is a mapping f: R -> R (or from another one-dimensional domain) whose behaviour can be studied by calculus, algebra and graphing; typical examples are polynomials, trigonometric functions and exponential functions of one argument.

In statistics and data analysis a ühemuutuja dataset or distribution contains observations on a single attribute (for example height or temperature). Univariate analysis summarises such data with measures of central tendency (mean, median), dispersion (variance, interquartile range) and shape (skewness, kurtosis), and uses visualisations like histograms, density plots and boxplots. Univariate probability distributions (normal, binomial, Poisson) model the behavior of one random variable.

Univariate models include simple linear regression with one predictor and ordinary differential equations in one variable. Advantages of focusing on a single variable are simplicity and clarity; limitations include inability to capture interactions or dependencies between multiple variables. Techniques for extending univariate work include multivariate analysis and multivariable modelling. The term underscores analyses or mathematical objects constrained to one degree of freedom.