regression

/ri gresh"euhn/, n.

1. the act of going back to a previous place or state; return or reversion.

2. retrogradation; retrogression.

3. Biol. reversion to an earlier or less advanced state or form or to a common or general type.

4. Psychoanal. the reversion to a chronologically earlier or less adapted pattern of behavior and feeling.

5. a subsidence of a disease or its manifestations: a regression of symptoms.

adj.

6. of, pertaining to, or determined by regression analysis: regression curve; regression equation.

[1510-20; < L regression- (s. of regressio). See REGRESS, -ION]

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In statistics, a process for determining a line or curve that best represents the general trend of a data set.

Linear regression results in a line of best fit, for which the sum of the squares of the vertical distances between the proposed line and the points of the data set are minimized (see least squares method). Other types of regression may be based on higher-degree polynomial functions or exponential functions. A quadratic regression, for example, uses a quadratic function (second-degree polynomial function) to produce a parabola of best fit.

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