The tone of scepticism adopted by Reserve Bank senior officials in their comments about macroprudential policy to a parliamentary committee on Friday is echoed in documents the RBA released yesterday in response to Freedom of Information requests.The batch of documents included several papers on macroprudential policy by the head of the RBA's financial stability department, Luci Ellis. Among her observations, she said some macroprudential tools did not conform to good credit risk management practice.Ellis also said there had been insufficient independent evaluation of the effectiveness of macroprudential policies and that some influential papers on the matter had not been subject to peer review.Macroprudential policy involves the use of a set of non-interest rate tools to stabilise house prices and housing credit. These tools include the application of reserve requirements, maximum debt service-to-income ratios, maximum loan-to-valuation ratios, limits on exposure to the housing sector and housing-related taxes."A dispassionate analysis of recent banking crises shows that, aside from the recent US episode, the source of banks' distress is not usually the mortgage book," Ellis said."It is possible to get into trouble in mortgage lending to households, so risks from this market must be given at least some weight," she said."Property development loans are a more likely source of loan losses. More often than not, the element of the financial boom-bust cycle that produces financial sector distress is quite unrelated to housing." On the subject of risk management practice, Ellis cited the example of how a uniform ceiling on debt servicing ratios ignored that different borrowers may have different debt servicing capacities out of the same income because their situations were different. "Competent lenders take account of these differences," Ellis said.Reserve Bank governor Glenn Stevens told the House of Representatives economic committee on Friday the RBA and the Australian Prudential Regulation Authority had been looking at the issue.Stevens said the most useful tool might be to increase the interest rate buffer that lenders used when they tested a borrower's ability to continue servicing a loan when rates rose.APRA could insist that the test applied to a borrower could be made 300 or 400 basis points higher than the existing test of, for example, 200 basis points, he said.RBA deputy governor Phil Lowe told the committee macroprudential tools were very much like the tools the central bank used in the 1970s."We ended up deciding we did not like those very much because you restrict one class of lenders, and the financial system is very flexible and another class of lenders comes up to fill [the gap]," Lowe said.