1. The structure of linear models The general expression for a straight line y=a+bX cRy and X: dependent /independent variables of interest CRa and b: constants, coefficients, parameters a: Intercept--- y=a+b(o=a b: Slope(Gradient) b=the change in y/unit change in x =△y△X1. The Structure of Linear Models  The general expression for a straight line: y=a+bx y and x: dependent /independent variables of interest a and b: constants, coefficients, parameters  a: Intercept--- y=a+b(0)=a  b: Slope (Gradient) b=the change in y/unit change in x =y/ x