One of the most active areas in analytical tools related to green chemistry and engineering is that of quantifiable metrics.  There are important measures of (process) mass intensity ((P)MI), reaction mass efficiency (RME), carbon efficiency (CE), innovative green aspiration level (iGAL), and others.  These quantifiable metrics can be useful and informative in answering specific questions of efficiency and environmental impact when a reductionist analysis is necessary to inform improvement.  It is as important to know what data or information the quantifiable metrics are providing as it is to understand what questions they aren’t addressing. The strengths of quantifiable metrics are essential and their weaknesses must be equally respected.