The arbitrariness of the long distance projection

News stories about the current population debate tend to be prefaced with the factoid that ‘on current trends Australia’s population will reach 35 million in 2050’. We are supposed to find this startling, either because we’ve only just adjusted to the idea of our millions being in twenties, or — if we’re a bit more sophisticated — because we remember that 28 million was the figure previously tossed around, having originated with an ABS release in 2001.

The way the issue is framed, we are each supposed to adopt a position on this — to follow the Prime Minister and bravely embrace the challenge, follow Bobs Carr and Brown and demand that the brakes be applied, or follow Harry Triguboff and bemoan the timidity of our leaders in aiming below 100 million.

But the thing about this 35 million projection, drawn from the Treasury’s 2010 Intergenerational Report, is that, just like its predecessor, it’s plucked out of the air. The natural part of the population growth rate, births minus deaths, is scientific enough, based on the current age structure, and plausible extrapolations of trends in life expectancy and fertility. Natural growth accounts for nearly half of the projection, but the outcome is not very sensitive to variation of the parameters over the plausible range — so errors in the assumptions won’t change the forty-year forecast by more than a million or so in one direction or the other.

However, the contribution of net migration could be anything. There seems to be an assumption that the projection for net migration is based on recent numbers. For example, Martin Bell, quoted in Crikey:

the surge in growth reported in the latest ABS stats is largely a product of unprecedented levels of overseas migration, coupled with a large number of overseas migrants being counted as permanent residents. No one who has looked closely at this data expects this level of growth to be sustained even for the next five years. … speculation about a figure of 40 million shows the manifest dangers of basing long term projections on trends over the latest year or two.

But the basis of the calculation is both cruder and stranger. As the graph shows, the IGR simply assumes that the average rate for the next forty years (as a percentage of the population) will be the same as the average for the last forty years. And rather than assuming that the rate will stay at six percent, the projection supposes that the level of net migration is constant over the four decades at 180,000, so that it falls from roughly seven to roughly five percent over the period.

The demographer Bob Birrell puts it like this:

If Australia reaches 35 million by 2050, choices about desired family size will play a minor role. The projections all assume that fertility will remain below the long-term replacement level. As a result, some 85 per cent of the projected growth from 22 million today to 35 million will derive from net overseas migration (including children born to migrants once in Australia).

There will never be knock-down argument in favour of any population target for Australia. The announcement of Tony Burke’s new portfolio will calm everyone down and diffuse the issue until after the election. When it comes out, his report will be quickly be forgotten unless he recommends a startling revision of the current immigration intake, and I’ll be amazed if he does.

If we consider only the interests of the incumbant residents, it’s hard to produce good arguments in favour of doubling the population. At best we can point to some studies showing that previous immigration has not made us worse off in terms of standard indicators like GDP per capita and the unemployment rate. However, in terms of broader well-being, life is getting less pleasant in our increasingly crowded cities. The only concrete argument you ever hear is that with greater urban density public transport would be more affordable. But that’s a case of the tail wagging the dog if there was one: the problem could be just as easily solved by better urban planning.

Then there are arguments that we need immigrants to fix particular imbalances in the skill or age profiile. Even if this was right, it’s hard to say that more than a million or two would be needed to achieve the adjustment. On the other hand, if there is a chronic tendency to disequilibrium in skills or age profile, whatever that might mean, no amount of immigrants would be enough to fix it permanently.

Finally of course there’s the traditional hidden agenda behind the bipartisan approach to immigration — national defence. But these days air supremacy and expensive missile systems, rather than infantry numbers, seem to be the key to defending territory from invaders, so I doubt if that argument will be made even in defence circles, though some still embrace it.

Therefore, the issue boils down to whether we’re prepared to share our space and economic opportunities with the less fortunate people abroad who want to come here.

Many of the issues are covered in posts by Robert Merkel and John Quiggin, both followed by comments threads that are more illuminating than all of the MSM offerings of the past week.

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14 years ago

in terms of broader well-being, life is getting less pleasant inour increasingly crowded cities

A widely circulating meme, but how many people have stopped to think whether it is actually true – and whether, if it is, the main problem is density of people per hectare?

more affordable public transport <= better urban planning <= greater population density.

14 years ago

When it comes out, his report will be quickly be forgotten unless he recommends a startling revision of the current immigration intake, and I’ll be amazed if he does.

I wouldn’t be entirely sure of that. If Pauline Hanson mk II turns up to take advantage of the current hysteria, who knows how the government will respond. I also don’t think that just being relentlessly cruel on boat people will work any more since the main drivers are now things to do with the general number of people, not just paranoia.

it’s hard to produce good arguments in favour of doubling the population

I’m not sure that one needs an exact doubling or any particular figure, but given (a) aging; (b) the degeneration of maths and science in our schools; and (c) the degeneration of standards in our universities, I think that people take the idea that we have certain industries and standards for granted, and don’t understand immigration’s role in this. Let’s say we stopped immigration tomorrow — I think the ignorant consensus is that those of a working age would be far better off. However, the alternative is that many of our easily replicable industries simply disappear offshore (which is almost everything except mining), and those that are left end up with far lower workplace productivity levels since we wouldn’t have enough engineers, medical staff, IT staff, scientists etc — all the people we are dependent on immigration for now. If this is the case, everyone could be far worse off. Now, I don’t have the foggiest idea of how many immigrants we actually need to stop this happening, however, even with moderate numbers, we will still end up with a reasonable population increase over time.

14 years ago

Dear Conrad,
With regard to –
“it’s hard to produce good arguments in favour of doubling the population”

Let’s just adjust that a little and the brainwracking problem will be dealt with in a very traditional way.

Here goes –

“It’s easy to produce good armaments in favour of decimating the population”.

There. Problem solved.

14 years ago

Well, there you have it Jacques.

In reply to yours –

Different standards and specs in different industries which in a well organised world should become standardised.

When you talk about a “cone of uncertainty” – in my game we give it a few different names depending upon what order of equipment we’re playing with.

In general terms though you allude to a lack of precision around and about your aiming mark – something, as you admit to in your field, leads to angst.

Whereas in my old trade we design and build our product to deliver the payload exactly within the specified tolerance and with exactly the correct, customer specified and required, effect.

Since I’ve said that you probably haven’t a clue as to what I mean.

But consider that the “future uncertainty” you mention has mainly been caused by the futility of number crunchers and pragmatists being artificially placed before originators, innovators and producers for too many years in this backward society.

Yes. It is true.

I am one of the presently disenfranchised in this dump nation.

I am completely unable to go out to work for the brain dead.sort (not that I’m suggesting any of my colleagues here, especially Jacques, are such) who presently rule the hutch.

I’m one of the creative lot that have no say or influence in modern Australia.

When Australia was looking good industrially just after WW11 my lot used to employ drifters from the bean counter set to tidy up the details and send out the bills to our customers. At their limit of expertise then they were halfway useful for that.

It strikes me that since then and with the advancement of electronics and all those tricks- the worm has turned.

From where I sit (and I’m sure that if Douglas Adams was still alive; he’d agree) it seems that the ‘pursers’ have taken over with their very inexact craft to the detriment of all concerned from the top of the high Himalayas to beside the shores of the Dead Sea.

Meanwhile China is doing well: India is doing well – and selling on into Australia, Europe and the US – cheap commodity goods of about the same merit as the junk we sold them when we first intruded upon their shores.

We have learned nothing; absolutely nothing at all.