For every measure, there's a decision that's taken as to whether or not to continue to do it, to not do it, or to change it in some fashion. I can only speak to the fact that the government has decided to continue this credit on an annual basis.
I'm not aware of any study to look at the specific kind of impact that you're talking about. In terms of evaluating the utility of credits, the department also relies on input from stakeholders and certainly there's been enough of that.