There's an excellent discussion of a recent finding in development economics over here.

If markets are missing completely, or so unreliable as to effectively be missing, then household separation fails. The extreme case is easiest to think of. If a household is completely autarkic, and can trade with no one else, then it can only consume what it produces. The two decisions are inseparable. If they want a new TV, then they’d better have a source of rare earth elements in their back yard and a passion for soldering.

The importance of knowing if household separation holds or not is that it tells us something fundamentally important about why a developing area is poor.

What's being looked at is that horrible, $1 a day, poverty that far too many of our fellow humans are stuck in. The big question being, well, are they stuck there because of the way that markets operate? Perhaps "the market" means they can't get enough fertiliser for example. Or is it that markets simply do not exist and thus they cannot reap the benefits of the division and specialisation of labour and the subsequent trade in the increased production?

The answer appears to be the absence of markets rather than any failure in them. Which leads to an interesting thought about what should be the right way to aid them.

Instead of sending money with which to buy them stuff we should be trying to work out how to create markets. And the most important part of that is in fact information. Not from us to them, but within such communities. And that ties in neatly with something that is becoming apparent from another part of the literature. It may well be that the mobile telephone is the greatest poverty reducing technology of our times. Simply because it does do exactly that, allow the spread of the information that enables markets to do their wealth creation thing. As this excellent paper makes clear.

It's not quite as simple as "make sure there's a phone network everywhere and the poor will get rich" but we're increasingly coming to the view that that's a damn good start to solving the problem.