We propose a set of variables to be used in place of the customary energies and angles in the analysis of quasi-free scattering data. In terms of these variables one can reduce the usual fivefold differential cross section to a threefold differential including the effects of experimental acceptance without resorting to Monte Carlo techniques. In this form the dependence of the data on nuclear and two-particle variables is clearly separated. Finally, two simple tests of the impulse approximation, the Treiman-Yang test and the Chew-Low extrapolation, can be applied directly to the data in particularly simple form.