The Reserve Bank of Australia yesterday publicised some alternative measures of housing affordability that analyse the issue from the standpoint of typical purchase patterns.One widely reported measure in this debate is the regular series promoted by Commonwealth Bank and the Housing Industry Association. On this pair's measure the "average" household at present has 93 per cent of the disposable income a bank would require to buy a house, using the median first home-buyer's price of $437,000. Two-and-a-half years ago the ratio was 115 per cent.The RBA attempted to model the income of younger (that is, new home-buying) households from 25 to 39 and assess affordability from the view of this cohort. The estimates suggest that in four of Australia's five major capitals, around 30 per cent to 35 per cent of houses and flats sold in 2006/07 "have been accessible to the median household in the home-buying age groups". Perth was the exception, where only around 10 per cent of dwellings would have been accessible to home-buyers in that age group. The RBA estimates that, nationwide, on average around 33 per cent of houses and flats sold would have been accessible to the median young household in 2006/07, compared with a longer-run average of around 45 per cent. So, the RBA agrees that housing affordability is worse than before.As to what, if anything, to do about this the RBA cautions that demand-side measures (such as grants) simply end up capitalised in purchase prices and instead advocates reform on the supply side, such as land zoning.