Just for the record my definition of an identification strategy is not quite right -- it should be > a way for assessing the impact of x (downloads on sci-hub)

Just for the record my definition of an identification strategy is not quite right -- it should be > a way for assessing the impact of x (downloads on sci-hub) on y (citations) which _identifies_ a source of variation in x, that is independent of y, except through its impact on x. There are a bunch of different ways that people express this. One is that there are no backdoor paths between x and y. Another is that X should be uncorrelated with the error term of the model.