On the foreign policy side, that is also a long-standing debate in academic circles: How do you measure success on sanctions? Part of the difficulty in answering that question is that in many cases the stated object of sanctions is not the same as the de facto objective. In many cases—Cuba, Iran, or even Russia, for that matter—the stated objective is to change the regime's behaviour. It's not happening. The de facto objective becomes to weaken the adversary, because it won't change its behaviour. That can be measured, but it's very difficult.
In the case of Iran, one of the never-ending debates is this. Iran's economy is struggling in many ways: negative economic growth, double-digit inflation and very high unemployment. How much of that is because of sanctions, and how much is because of mismanagement? It's very hard to say.