The judgment call the bank is making is that there has been an enduring shift to saving more of our incomes and spending less.
Data published by the bank this week show that over the course of 2012 household debt rose 3.5 per cent to $192 billion, driven by a 4.5 per cent increase in mortgage debt to $178 billion.
That outstripped the growth in disposable (or after-tax) incomes, so that by the end of the year household debt was the equivalent of 145 per cent of disposable income, up from 142 per cent in December 2011.
It is down from the peak of 153 per cent in 2008, but still a high ratio by historical standards, and it is not good to see it deteriorate.
The reassurance comes from looking at the other side of the balance sheet and what has happened to households' financial assets over the same period.
In the course of 2012 household financial assets rose $21 billion or 9.6 per cent to $240 billion - a more rapid increase than the 3.5 per cent rise in debt.
The biggest factor was an increase of $9 billion to $115 billion in bank deposits, despite dispiritingly low interest rates. It is one of the reasons the Government is confident its power company floats will be snapped up.
Superannuation and managed funds rose $8 billion to $74 billion and directly held shares rose $5 billion to $27 billion. Much of those increases would reflect revaluation gains from a good year on equity markets. But the active saving proportion, in the form of continued inflows into KiwiSaver schemes in particular, would have been substantial too.
Now, it is true that the accumulation of debt accelerated during the course of the year.
The annual growth of 3.5 per cent in December was an increase from 2.3 per cent in the September year, 1.7 per cent in June and 1.2 per cent in March.
But the pace of growth on the financial assets side climbed as well.
The 9.6 per cent annual growth recorded in December, was up from 8.7 per cent in September, 4.3 per cent in June and 3.6 per cent in March.
Households ended 2012 with net financial wealth of $48 billion, up from $37 billion a year earlier and just $12 billion in 2008.
Relative to disposable income it was 36 per cent, the highest since 39 per cent in 2004.
And these figures only record financial assets. They do not take account of housing assets, or businesses and farms, or other assets owned by households.
Even so they paint a picture of some collective prudence, with households' financial assets exceeding, and growing faster than, their debts, and with active saving (as opposed to the gains from rising share prices), like bank deposits, growing faster than mortgage debt.
Measuring changes in the stock of assets and debt is only one way of measuring saving rates, however.
Often cited is a flows measure, which takes an estimate of household income, subtracts an estimate of household spending and expresses the difference as a percentage of income. Statistics New Zealand's household income and outlay account, part of the national accounts, is the source of the data.
It makes depressing reading. It shows households dis-saving, that is, spending more than their disposable income, in 17 of the past 19 years.
The trend has been improving over the past 10 years, however.
We even made it into the black (just) in the year to March 2011 before slipping back into the red the following year. The Reserve Bank's forecasts have it stabilising around break-even, give or take 1 per cent of disposable income, over the next four years.
This flows measure of the household saving rate is viewed with suspicion by some economists, in the Treasury in particular.
It has been subject to large revisions over the years.
In 2007, for example, the statisticians told us households the year before had spent $1.15 for every $1 of income. They now say it was $1.08 - not good, but not quite as bad either.
Also economists struggle to reconcile it with stocks-based measures like the Reserve Bank numbers above, which paint a systematically less feckless picture of household behaviour.
A paper by Treasury economists Emma Gorman, Grant Scobie and Yongjoon Paek last month concludes: "In applying the stock measure to aggregate household sector data on assets and liabilities we find the long-run average saving rate was 16.1 per cent of household disposable income (from 1979 to 2011).
"After stripping out the effect of house price revaluations (the passive component), which amounted to an annual average of 8.9 per cent, we are left with an estimate of an active annual average household saving rate of 7.1 per cent."
In contrast, over the same period the flows measure from the national accounts averaged minus 0.7 per cent of household disposable income a year.
They add that when the flows measure is adjusted for spending which might more appropriately be defined as investment, such as education, and for the impact of inflation, saving rates are significantly increased, by an average of 4.4 percentage points between 1996 and 2011.
The latest Westpac McDermott Miller survey of consumer confidence found the net balance of respondents who say they are better off financially than a year ago is the highest since late 2007, though still well below the levels of the mid-2000s boom.
Their willingness to spend on a big household item is also close to post-2006 peaks.
"Historically these are the parts of the survey which have been most relevant to actual spending," Westpac economist Felix Delbruck said.
But it was too early to say the survey results challenged the Reserve Bank's view of a still-cautious consumer limiting the risk that the strengthening housing market will supercharge household consumption and spill over to consumer price inflation.
