Quantifying Sanctions?

As a news junkie, I spend a lot of time on Twitter and all of the relevant foreign policy news sites. On these sites there is a relatively healthy debate over the efficacy of sanctions against Iran, but the lack of geographic thinking in the discussion is disheartening. By 'geographic' I do not mean just the physical space itself, but rather a more complete holistic approach. 

Both sides vociferously argue that their opinion is valid, while listing a variety of reasons. Those in favor of sanctions point to the lack of diplomatic progress in negotiations as proof that more drastic measures are necessary, namely increased sanctions, with the potential of military action if Iran does not change its behavior. Those opposed to sanctions talk about how the sanctions are rather crudely implemented, restricting humanitarian goods like medicine. Others who are opposed to sanctions believe that the measures are not enough, and the lack of any significant concessions by Iran means that the West must react militarily to prevent Iran from obtaining a nuclear weapon (or the capability to build a nuclear weapon). I am not going to write about these arguments because the specifics details are not as interesting to me. I am much more interested in the big picture, which is why the lack of a comprehensive discussion of the entire situation is disturbing to me. 

It is certainly true that Iran's production of nuclear material has increased significantly since the various sanctions were implemented, but how can one measure the true impact of these sanctions? Do we look at the rapidly falling value of Iranian currency and the rampant inflation? Do we look at year by year or month by month comparisons of how much petroleum based products are exported by Iran? Do we look at the Iranian budget as an indicator of financial health? Do we look at the number of centrifuges used by Iran, or the quantity of enriched uranium which it has? 

Some will say that the increasing number of centrifuges which Iran is using indicates that sanctions are not having their desired effect. This is certainly possible, but what may be overlooked by this estimation is the possibility that Iran's rulers have placed an increased importance upon their nuclear program as a way to gain leverage with the West. From their actions, it seems as though the Iranians act rationally, couldn't this be an expression of their rationality? When one is put into a difficult situation isn't it natural to try and gain leverage in whatever way possible? 

Assuming some sort of interconnectivity between all things, claiming that sanctions are not having an effect on Iran is a ridiculous notion. Following this logic, won't there then be at least some impact on Iran's nuclear program? Iran does not exist in a vacuum, and its various governmental programs are similarly not isolated from every other part of the country's governmental apparatus.

Just because it is very difficult to quantify the impact of sanctions upon a program, this does not exclude the possibility of there being some sort of connection. The sanctions, while crude at best, clearly have had some sort of impact on Iran. While the effect of and the ability to measure sanctions on Iran's nuclear program is debatable, what is certain is that insufficient measurements using simplified methods will lead to simplistic, insufficient conclusions.