The changes to OSFI's rules and other changes are not the normal things that are in macroeconomic models, whereas interest rates are obviously in our models. It requires a little extra and more innovative analysis. We have microdata, which was alluded to earlier.
We know, for example, how many people who qualified for mortgages in 2016 will not qualify for them under the new rules and how much less they can borrow. We were able to do almost a simulation, as if we had put the rules in place earlier. We can do that and we can then translate it into an approximate effect on the economy, on the order of 0.2 or 0.3 percentage points in the subsequent year or two of GDP. If it's growth, then it might be half that over two years, or if it's faster it will be all in one year.
Importantly, the way one reacts is an individual decision. Here are the new rules; what do you do? This is the house you wanted to buy, and now you don't qualify. Is your reaction to postpone for a year? Possibly. Is your reaction instead to say, “I think the house next door, which is a little smaller, suits my needs as well, so I'll buy that one instead”, in which case you still go ahead with the transaction.
It's very hard to know how it actually translates into GDP impacts. This is exactly why we say, with the new level of interest rates today compared with those of six months ago, that we need to monitor very carefully how people are actually behaving in real time. We can't just rely exclusively on our models to do that.