When you're building a price index, it's more about the issue of controlling for the variation and the quality of the housing. Otherwise, the price movements may simply be a change in the average quality of the housing. It's about controlling for those kinds of factors, and that is not their intent, so I'm not faulting them or suggesting that their data is unreliable for any purpose for which people may currently be using it.
As I said, in talking to Finance Canada, the sponsors of this particular project, the conclusion was that the data really wasn't quite robust enough for the purpose.