linear regression vs regression

linear regression and regression both are nouns.

Word	Noun	Adjective	Verb	Adverb
linear regression	Yes	No	No	No
regression	Yes	No	No	No

As nouns, regression is a hypernym of linear regression; that is, regression is a word with a broader meaning than linear regression:

linear regression: the relation between variables when the regression equation is linear: e.g., y = ax + b
regression: the relation between selected values of x and observed values of y (from which the most probable value of y can be predicted for any value of x)

Other hypernyms of linear regression include regression toward the mean, simple regression, statistical regression.

linear regression (noun)	regression (noun)
the relation between variables when the regression equation is linear: e.g., y = ax + b	returning to a former state
	the relation between selected values of x and observed values of y (from which the most probable value of y can be predicted for any value of x)
	(psychiatry) a defense mechanism in which you flee from reality by assuming a more infantile state
	an abnormal state in which development has stopped prematurely