Measure housing affordability in Australia

Comments on Gennadi Kazakevitc, Lionel Frost and Luc Borrowman "Just how stressed are we when it comes to housing affordability", 9/05/2013, http://theconversation.com/just-how-stressed-are-we-when-it-comes-to-housing-affordability-13937
Genadi, Lionel and Luc, the methodology you mentioned in this article is obviously a step n the right direction and you should all be congratulated for making and using it.
Another method could be simply use a ratio of average housing costs to household disposable income. Average housing costs can be defined by renting costs and/or by average mortgage payments, or a combination of them in some weights.

In answer to Gennadi's reply: "Lincoln, Many thanks for your comment. Unfortunately, using average housing costs in the ratio does not help avoiding the fundamental problem with the ratio approach - it does not allow for singling out the groups/types of households that are really in stress."

Thanks Gennadi. Is it possible to calculate the ratios by groups/types then compare and rank them to form an order of stress?
I've though such ratios would produce better measurements, i.e. irrespective rent of buying, different preferences in terms of voluntarily paying more or less and the differences in size of houses/properties, etc, as well as the stages of mortgage payments.
Anyway, it may be my thought bubbles is bubbling.