Mental reversion to a younger age, used in therapy, as a coping mechanism, or as a manifestation of a psychiatric issue.

(psychology) A period of days or weeks during the first two years of life characterized by a change in an infant's sleep patterns, leading to irregularities such as increased awakenings and fussiness.

(statistics) A linear equation for deriving a single predicted value from one or more known explanatory values.

plural of regression to the mean

plural of regression tree

(derogatory, politics, rare) The politics of the regressive left.

(data mining) A data-analysis method that recursively partitions data into sets each of which are simply modeled using regression methods. / A classification and regression tree.

(software engineering) Testing a program after a modification to ensure that areas that should not be affected by the update behave as they did in previous versions.

(statistics) The phenomenon by which extreme examples from any set of data are likely to be followed by examples which are less extreme; a tendency towards the average of any sample. For example, the offspring of two very tall individuals tend to be tall, but closer to the average (mean) than either of their parents.

(derogatory, politics) A characterization of the left which suggests that it paradoxically holds reactionary views by its tolerance of illiberal principles and ideologies (such as extremist Islamism) for the sake of multiculturalism and cultural relativism.