Assuming that the underlying propensities are, in fact, stable and given enough time-series data with sufficient variation, standard regression procedures should be able to extract reasonably robust  BIS Review 73/2001  1  estimates of any differential in spending propensities - for example, out of stock market wealth and home wealth. But, in practice, these circumstances do not prevail.
Current or past developments, such as the latest available inflation outturn, are only relevant to the monetary policy decision to the extent that they provide useful information about future developments, which may not be very relevant at all. This entails a qualitative shift in the way in which policy makers think about the economy and make decisions, to embrace a forward looking approach.