Material recovery uncertainty is measured as the MRR: the frequency that material recovered off a core unit is re-manufacturer (Guide and Spencer, 1997). The majority (95%) of re-manufacturing firms use simple averages to calculate MRR, although at least one firm responding used more sophisticated multiple regression models. Firms reported a wide range of stability for most MRRs, ranging from completely predictable to completely unpredictable. Products are equally likely to contain parts with known predictable recovery rates, as to contain parts with no known pattern of recovery.