• Probability of adversary success — The probability that an adversary will successfully complete a pathway and generate a consequence.

• Consequences — The effects resulting from the successful completion of the adversary’s intended action described by a pathway, including the effects of mitigation measures.

• Physical protection resources — The staffing, capabilities, and costs required to provide PP, such as background screening, detection, interruption, and neutralization, and the sensitivity of these resources to changes in the threat sophistication and capability.

Measures can be estimated with qualitative and quantitative approaches, which can include documented engineering judgment and formal expert elicitation. Measures can also be estimated using probabilistic methods (such as Markov chains and event trees) and two-sided simulation methods (such as war-gaming techniques). GenlV International Forum (2011b) reviews a number of system analysis techniques relevant for PR&PP studies.