This difference is called its residual. A residual plot charts these values against the first variable to visually display the effectiveness of the equation.

This paper defines partial residuals in multiple linear regression. The ith partial residual vector can be thought of as the dependent variable vector corrected for all independent variables except ...

Also, many tests of proportional hazards, including those of Cox (1972), Gill & Schumacher (1987), Harrell (1986), Lin (1991), Moreau, O'Quigley & Mesbah (1985), Nagelkerke, Oosting & Hart (1984), ...