Building on Shannon's lead, let's consider a more malleable expression for tracking uncertainty, and states of "knowledge available" vs. "knowledge missing," to better practice innovation, improve risk management, and successfully measure progress of intractable undertakings. Shannon's formula, and its common replacements (Renyi, Tsallis) compute to increased knowledge whenever two competing choices, however marginal, exchange probability measures. Such and other distortions are corrected by anchoring knowledge to a reference challenge. Entropy then expresses progress towards meeting that challenge. We introduce an 'interval of interest' outside which all probability changes should be ignored. The resultant formula for Missing Acquirable Relevant Knowledge (MARK) serves as a means to optimize intractable activities involving knowledge acquisition, such as research, development, risk management, and opportunity exploitation.