Retailers have suffered their worst two months since 2010, and there is a growing view among economists that it reflects a broader pattern of consumers becoming more cautious with their money.

If that turns out to be true, it's important not just for retailers, but for the whole economy. Why?

Because total consumption by the household sector accounts for about 55 per cent of gross domestic product - so a broad-based slowdown in spending can have widespread impacts.

Importantly, retail trade is not same thing as household consumption.

Retail trade accounts for about a third of total household consumption, which includes all the spending on other things such as energy bills, education, or health. It's unlikely total consumption will be as weak as retail trade because it's much harder to cut back on your electricity expenses, say, than your spending on clothing.

Even so, retail trade is an important indicator of how willing households are to spend their cash, and there are convincing reasons to think the weakness in retail is important for the economy.

In August, the Bureau of Statistics says turnover fell across key spending categories, including a 0.6 percent decline in food, a 1.3 per cent fall in cafe and restaurant spending, and a 1 per cent slide in household goods.

National Australia Bank's Alan Oster says it's not exactly clear why retail sales have been so weak lately, but there are plenty of things likely to be limiting spending growth.

Wages growth is still near a record low, utility bills are soaring, and there's been increasing speculation that interest rates may rise. We also have a problem with "underemployment" - people wanting more hours of work than they can get - and household indebtedness is at a record high.

All these causes of greater caution may well mean consumers play a smaller role in kicking along economic growth.

Over the next six months or so, Oster predicts the economy will receive a short-term lift from a ramping up in exports of liquefied natural gas, and a peak in the housing construction boom. That will push the annual pace of growth up to 3 per cent for this quarter and next, he predicts.

But for most of us, he says it probably won't "feel" like growth of 3 per cent, because household spending is restrained. And then later in 2018, once those one-off sources of stronger growth start to wear off, the softer underbelly of the economy will become more apparent.

"You're going to need the consumer to do better than what they are currently, which is why everyone is talking about the need for wages to go up," Oster says.

"Unless you get some wage growth, the consumer is going to be really cautious, and that just makes it really difficult."

Capital Economics economist Paul Dales points out another potential way in which household behaviour may soon change.

In recent years, consumers have been happy to save a lower portion of their income - therefore supporting their spending. It's likely this is partly the result of households feeling wealthier, thanks to the property boom.

But they may be reluctant to continue cutting back on their savings when the biggest asset most people own - their house - is no longer gaining value as it has.

Having said that, we shouldn't overstate the recent weakness in spending. Dales says it's a "worry, not a disaster", pointing out that jobs growth has recently been strong, which is generally good news for spending.

However, the recent slowdown in retail suggest there is a change in the composition of growth, so that it is being driven more by commodity exports, and less by households. If that ends up being the case, Dales suggests it may make the Reserve Bank more hesitant to raise interest rates next year, as financial markets are betting.