Looking back on 2014, there is no doubt it was the year of the self-proclaimed Islamic State (IS) occupying parts of Syria and Iraq.

In recent days, Western media have increasingly reported that IS is unable to sustain its May-August blitzkrieg and that this may well be the beginning of the end for the group. Reporters say that IS has lost its initial popularity, that its power on the ground is waning, that combat with IS has reached a military stalemate and that, this time, it's the coalition’s turn. Improved Iraqi security forces are pushing back IS fighters, they report, and some analysts have even developed scenarios for the post-IS period.

But it's a tricky thing to measure the demise of the group. How can one know IS is losing? What military metric should we use? Is IS still growing, or can we assume that its collapse has already begun?

Of course, certain indicators justify this optimistic picture. In particular, IS' inability to capture new territory since September 2014; their setbacks in Sinjar against the peshmerga; their failure to capture Kobani, which IS initially saw as easy prey; severe restraints on IS fighters’ mobility due to coalition air attacks; the fading influence of their professional (and savage) media; and decreasing oil prices, which appear to have struck a blow to their financial resources.