: a trend or shift toward a lower or less perfect state: as
a: progressive decline of a manifestation of disease
b (1): gradual loss of differentiation and function by a body part especially as a physiological change accompanying aging (2): gradual loss of memories and acquired skills
c: reversion to an earlier mental or behavioral level
d: a functional relationship between two or more correlated variables that is often empirically determined from data and is used especially to predict values of one variable when given values of the others <the regression of y on x is linear>; specifically: a function that yields the mean value of a random variable under the condition that one or more independent variables have specified values
: a trend or shift toward a lower, less severe, or less perfect state: as a: progressive decline (as in size or severity) of a manifestation of disease <tumor regression following radiation>b (1): a gradual loss of differentiation and function by a body part especially as a physiological change accompanying aging <menopausal regression of the ovaries>(2): gradual loss (as in old age) of memories and acquired skills c: reversion to an earlier mental or behavioral level or to an earlier stage of psychosexual development in response to organismic stress or to suggestion <a protective regression towards childhood—Havelock Ellis>
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 (seeleast 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.