A graphical method is characterized for estimating seismic velocity directly from diffraction patterns observed on common offset records. The nature of the resulting estimate is examined by illustrating the connection between the graphical approach and a related method used by practitioners of ground penetrating radar. While the latter provides only a crude stacking velocity, the graphical technique yields the generalized rms velocity for stratified media. Associated interval velocities can be derived from two or more diffraction events having their sources within the plane of survey. Where there is a lack of geological evidence to suggest that scatterers reside in-plane, we propose a simple strategy for locating a scatterer from its expression on two or more independent records. Error in the resulting location is directly related to subsurface velocity heterogeneity. Finally, since the diffraction-based velocity estimates assume that source and receiver are coincident, the error stemming from nonzero offset is characterized.