their ccyb frameworks in this direction. at the ecb, we strongly support this positive neutral cyclical buffer approach. with this characterisation of the conjunctural situation, let me offer a few specific reflections on how research can support policy - making in the face of current challenges. the first concerns macroprudential capital buffer releases. deciding the appropriate timing for the release of accumulated macroprudential buffers is challenging. in our view, this decision should be linked to clear constraints in the supply of bank credit due to banks'capital positions. while research so far has focused on broader macrofinancial signals for capital releases, i see scope to complement this work with analyses of conditions and banks'behaviour that would justify releases. this would surely help making capital releases more effective in reducing the pro - cyclical effects of bank credit in periods of economic distress. the second reflection concerns positive neutral capital buffers. as i have mentioned, this approach is increasingly being used across countries, including those in the banking union. models to assess the overall benefits of the positive neutral versus a purely risk - based buffer framework could be very useful in substantiating policy makers'support for this approach. 2 / 3 bis - central bankers'speeches finally, so far, i focussed on macroprudential capital. but this year reminded us that also liquidity issues can become quickly systemic. on the one hand, we saw shocks to market liquidity in the united kingdom last autumn, when price falls in core government bond markets led to forced selling by non - bank financial intermediaries, and risked becoming self - reinforcing. on the other hand, earlier this year we saw shocks to funding liquidity, where deposit redemptions at an unparalleled speed led to the largest ever bank failures in the united states, and the abrupt merger of a global systemically important swiss bank following liquidity outflows. these episodes are a stark reminder that more efforts are needed to understand and mitigate systemic liquidity risks. increased digitalisation and use of social media may at some point require a review of the design of microprudential liquidity standards for banks, such as the liquidity coverage ratio. more importantly, the gradual and systemwide decline in liquidity implies that a macroprudential perspective on liquidity will become more relevant going forward. in principle, the existing regulation already provides some scope to introduce liquidity measures for systemic liquidity risk for banks.

for the consumer price index. some of the prices in the consumer price index vary considerably, however, due, for example, to tax changes, weather and wind. changes in these prices provide little information about inflationary pressures in the economy. therefore, some central banks focus on an underlying measure of inflation. this may be the consumer price index excluding prices that fluctuate most, or measures such as the trimmed average or the weighted median. while the purchase and sale of a dwelling is an investment, the advantage we derive from using the dwelling – shelter services – is part of consumption. therefore, the price of shelter services should be included in the consumer price index. however, this is a price that cannot be observed and is difficult to measure. consequently, some central banks completely disregard shelter services. new zealand uses an index for construction costs, while iceland includes the market value of resale homes. as a rule, the price of shelter services will increase when the interest rate rises. all central banks disregard the direct effect of interest rates on the price of shelter services. this is also the case at norges bank. in very open economies, inflation may fluctuate somewhat without prompting fluctuations in domestic output and employment or leading to changes in inflation in the medium term. in such economies, it may be appropriate therefore to accept somewhat wider fluctuations in inflation. which prices to include in the price index is a topic of discussion. in the academic literature, some have suggested that the central bank can increase economic stability or reduce the negative effects of slow price adjustment by stabilising an index with fewer prices and weights other than those in the consumer price index. 3 prices that adjust slowly should have a relatively higher weight than prices that change quickly. prices for goods and services where labour costs are a major component often adjust slowly. 4 labour costs are very important in these indices not only because they change slowly but also because they react to cyclical movements and are seldom exposed to extraordinary disturbances. see aoki, kosuke ( 2001 ), “ optimal monetary policy responses to relative price changes, ” journal of monetary economics, vol. 48, pp. 55 - 80, arrazola maria and jose de hevia ( 2002 ), “ an alternative measure of core inflation, ” economics letters, vol. 75, pp. 69 - 73, mankiw, gregory and ricardo reis ( 2003 ), “ what measure of inflation should a central bank target? ” journal of the european economic association, vol. 1