Sentence:  For example , on the basis of the <WSD>regression</WSD> equation , a child with an I. Q. of 120 in this sample would be expected to earn an achievement test score of 4.8 ( grade equivalent ) . 
Meaning of the word marked with <WSD> tags:  the equation representing the relation between selected values of one variable (x) and observed values of the other (y); it permits the prediction of the most probable values of y