I think it's a good question. My colleague had started to talk about the methodology. We have implemented the best methodology possible. We have also very good interviewers who are convincing people to answer the questions. Obviously, these are very sensitive questions. There's no doubt about it. Is there under-coverage? We try to control it as much as we can. We have very consistent results over time, so we're fairly confident in our numbers. Recently we have tried all kinds of different techniques such as behavioural economics to nudge people, to convince people to respond. We've been phoning. We're very persistent, phoning about 25 times to try to convince people to respond to the question. But the response rates have been declining for sure, so it is a challenge to make sure there isn't under-representation of those people who are the most vulnerable.
On January 31st, 2017. See this statement in context.