Posts tonen met het label IQ. Alle posts tonen
Posts tonen met het label IQ. Alle posts tonen

maandag 5 maart 2012

Grow for it!

New Zealand, population 15 million. That's the target for 2060 in a new NZIER working paper making the case for substantial New Zealand population growth.
A population target of 15 million by 2060 (2.5 times that now projected) is not only “feasible”, it is also likely to be sufficient to achieve the benefits from scale. It would allow four main cities with a population of three million or more each. This would foster competition within New Zealand to create conditions amenable to building local firms that can foot it internationally. It would bring New Zealand’s population into close proximity of the Netherlands (but still nowhere near the population density of that country).
There's an awfully good case to be made for growth. Ed Glaeser's recent book makes a compelling argument that ICT is far more a complement to than a substitute for density - it makes everything better, but it makes New York better faster than it improves New Zealand. Australia will continue to benefit from agglomeration effects; stagnation relative to Oz fuels out-migration and worsening outcomes. Bill Kaye-Blake says we're doing fine given our distance - and he's right.
This changes the tone of the policy recommendations. It isn’t about claiming that the institutions (the tax system, the science system, the education system) are messed up and need to be fixed. Instead, it is about recognising that we’re pushing this economy uphill and asking what tools might help.
I think increased immigration should be on the policy agenda as a tool that can help in that context.

New Zealand is shifting immigration priorities to de-emphasize the family route and pull in migrants from higher up the income ladder. TVHE reminds us of the harm we do to poor foreigners abroad by such moves; we also do harm to ourselves to the extent that lower skilled workers are complements to high skilled labour - I'd certainly appreciate lower-cost domestic help.

The best counterargument is that there are potential external costs from lower-skilled immigration if we expect that income correlates with intelligence, intelligence is heritable, and intelligence matters for the long-term quality of policy in a democratic system and for overall productivity. Here's Garett Jones on how IQ matters.

So it's not crazy on the face of it to try to encourage high skilled immigration to New Zealand if we care about outcomes here rather than overall global welfare (I care about the latter, but that's me). But I would note that income will be a poorer proxy for IQ or skill differences if we're looking at individuals in a pooled international cross-section than within countries. Moreover, there's no real "lump of migrants" beyond which we can't accept more people. Why not make it easier for high income, high skilled people to move here while keeping the current family immigration route?

Potential policy moves that encourage immigration, and especially higher-skilled immigration? First on my list would be immediate permanent residence for any foreign student completing a Bachelor's degree at one of the New Zealand universities. This will not only boost foreign student enrolments (helping to cross-subsidize domestic students) but also provide a nice selection mechanism for those who are most likely to really make a contribution. We could also draw in high skilled American migrants by not losing our comparative advantage in civil liberties and sane copyright legislation.

Complementary to increased immigration would be fixing local land use policy that forces up housing prices, but that's also well worth doing for its own sake.

vrijdag 2 maart 2012

Genetics and investment

So, here are three results that demand reading as a set.

First, the new finding: there's a genetic basis for differences in investor behaviour when it comes to the standard behavioural biases that folks find in the lab. They use the Swedish Twin Registry combined with a whack of data that Scandinavian countries seem happy to provide to researchers on individual tax filings. They've eight years of data matching twins (mono and dizygotic) with portfolio characteristics and trading. The difference in the correlation between mono and dizygotic twin pair behaviours identifies the genetic component of trading biases - the standard way of identifying heritability in all kinds of twin studies. Conclusion?
We find that a long list of investment biases, e.g., the reluctance to realize losses, performance chasing, and the home bias, are "human," in the sense that we are born with them. We base this conclusion on empirical evidence that genetic factors explain up to 50% of the variation in these biases across individuals. The psychological mechanisms behind the investment biases have apparently survived natural selection over hundreds of thousands of years, presumably because they maximize (or in a hunter-gatherer society used to maximize) the likelihood of human survival and reproduction (e.g., Rayo and Becker (2007) and Brennan and Lo (2009)). But in our current society, and when applied in the domain of investments, they may not always be appropriate.
They also find that education does little to attenuate the effects of genetics on observed biases. Now, why might that be? Their method looks at the difference between monozygotic and dizygotic twins. But intelligence is also strongly heritable - the second (very old) finding. The linked meta-study puts heritability of intelligence at around 0.8 and up from age 18 onwards.  Now, does IQ have any effect on stock market behaviour?

Let's turn to the newly published, but not new to loyal readers, finding that IQ drives both stock market participation and portfolio characteristics. Smarter people are more likely to be in the stock market and are more likely to hold diversified portfolios correcting for education and income.

So, put it all together. Heritable intelligence drives education choices, stock market participation, and behaviour once in the stock market. Some of the heritability estimates that Cronqvist and Siegel are finding (the first paper) are probably working through the IQ channel that Grinblatt, Keloharju and Linnainmaa (the last paper) found.  Surprisingly, Cronqvist and Siegel cite earlier work by Grinblatt & Keloharju but miss the more recent piece.

There are papers combining Swedish Twin data with IQ measures; I'd be more confident in findings of heritability of stock market trading characteristics if they were able to sort twins into IQ brackets and show stronger monozygotic than dizygotic inter-twin correlations on trading among those bracketed sets of twins (or otherwise control for IQ). Suppose that IQ predicts education (but with noise) and that IQ predicts trading behaviour (also with noise). The mono vs dizygotic correlation difference that's identifying the genetic component of stock market behaviour could be picking up how IQ is affecting stock market behaviour rather than necessarily picking up an independent additional effect of genetics on behavioural biases. I'm not sure that controlling for education does a fantastic job in fixing that. I sure wouldn't throw away the Conqvist results on the basis of this, but as the IQ data is there, it's worth checking. Education isn't mediating the effects of genetics, on this account, because education is caused by heritable IQ. My econometrics aren't strong enough to say that for sure, or at least I haven't written out the model to check it.

Thanks to Robin Harrison and Seamus for a quick chat on econometrics; errors all mine as always.