Univariate

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In mathematics, univariate refers to an expression, equation, function or polynomial of only one variable. Objects of any of these types but involving more than one variable may be called multivariate. In some cases the distinction between the univariate and multivariate cases is quite fundamental; for instance the the study of roots of a polynomial only has a meaning in the univariate case.

The term is commonly used in statistics to distinguish a distribution of one variable from a distribution of several variables, although it can be applied in other ways as well. For example, univariate data is composed of a single scalar component. In time series analysis, the term is applied with a whole time series as the object refered to: thus a univariate time series refers to the set of values over time of a single quantity. Correspondingly, a "multivariate time series" refers to the changing values over time of several quantities. Thus there is a minor confict of terminology since the values within a univariate time series may be treated using certain types of multivariate statistical analyses and may be represented using multivariate distributions.