--- This blog post has been edited and updated based on new information sent to us about the relationship between IQ and income. We feel as though the evidence is more positive than we originally wrote but still not enough to change our conclusion that there is insufficient evidence of a connection between IQ and other positive life outcomes for us to value increasing IQ as a potential metric. ---
When looking at interventions in the developing world, you have the opportunity to improve a lot of things, from education, to job performance, to income, to reduced disease burden, to improved eyesight, to improved intelligence, and more. But how good are these things?
In “Six Examples of Measuring Incomplete Metrics …and How to Fix Them”, we shared a concern over “incomplete metrics” in non-profits, like web traffic or growth in budget size, that don’t get at the actual good produced by the non-profit. But when thinking about how to robustly define what is good, we realized that avoiding incomplete metrics might be harder to avoid than we thought.
When looking at increasing salt iodization, which is a GiveWell priority program rated to have “[r]easonably strong evidence of effectiveness”, we saw an opportunity to improve IQ. And this got us wondering -- how good is improving IQ? Could this be an incomplete metric or does it actually have a connection to the kind of good that we value?
Is IQ an end in itself?
In the book Utilitarianism, Mill said that “It is better to be a human being dissatisfied than a pig satisfied; better to be Socrates dissatisfied than a fool satisfied”. This argument has been taken to mean that intelligence is a good from a utilitarian perspective, insofar as intelligence is a key contributor to a life worth living. Thus even if your life is miserable, it would be better, on Mill’s view, than a life of only simple pleasures.
Other utilitarian authors would have disagreed with Mill. Bentham, whom Mill is arguing against, put forth a view that all pleasures are a part of the same “hedonic calculus” and thus it would be possible, at least in principle, for a satisfied pig to have a happier life than a sufficiently dissatisfied human being. After all, an opposite view is that “ignorance is bliss”.
Ultimately, we take this to be more of a value judgment and less of a question of empirical fact. Do you value intelligence for the sake of intelligence alone? Or do you only value intelligence as a means to an end, claiming the existence of empirical evidence that ties intelligence to a more satisfied life or an enhanced ability to create satisfying lives for others through intelligent works?
While looking for effective charity is hopefully an empirical matter, a lot of questions of what interventions are best depend on judgment calls about values that we believe cannot be fundamentally grounded in empirical research alone. We think reasonable people can disagree and this can change their opinion of which charity is the most effective, even if one looked at exactly the same empirical evidence.
Thus, we on the Charity Entrepreneurship team want to make it clear what we do and don’t value, which value judgment calls we are making, and how these affect our final judgments about which charity ideas we recommend.
Effects of IQ on things that matter
The value judgment that our team makes is that IQ is not a good in itself and that instead we want to find empirical research that substantially connects IQ to the outcomes we do care about, which are mainly that of improving psychological well-being.
When GiveWell talked with Dr. James Flynn, Emeritus Professor of Political Studies and Psychology at the University of Otago, he argued that a gain of four IQ points would be enough to allow someone to function independently as opposed to needing special assistance, that IQ improves job performance even on the menial jobs common among the extreme poor, and that gains in IQ would reduce the prevalence of intellectual disability.
Improving education and job performance seems good, but also just kick the can down the road. Sure, if someone does well in school, do they then go on to have an increase in well-being? If someone is better able to function at their job, do they go on to have an increase in well-being?
Presumably there could be a complex chain of impact, whereby an increase in IQ boosts job performance, which boosts income, which boosts the ability to provide food for oneself and one’s family, which boosts well-being. But this chain is complex enough that it could be reasonably doubted and empirical evidence would have to establish it.
IQ and subjective well-being
Empirical evidence does show some connection between intelligence and well-being. Academics have mainly looked at the connection between IQ and “subjective well-being” (SWB), which is one way to capture well-being that we like as a metric, but it has pros and cons that we intend to elaborate on in a future post. When looking at the benefits of IQ, we’re open to finding connection between IQ and any other metric that we find important, like DALYs, SWB, or income.
Cross-country studies find a connection between IQ and country-wide life satisfaction (Salahodjaev, 2015). However, it is less clear if there is an effect on the individual level. Diener and Fujita (1995) found a 0.17 correlation between IQ and subjective well-being in their developed world subjects after controlling for other factors, and they suggested that IQ fits in with a much broader view of “personal resources” that is much more highly predictive of SWB. Moreover, Diener and Fujita argued that personal resources would play a very different in a developing world context where immediate needs (e.g., food) are more dire.
Additionally, a 40-year longitudinal study in Luxembourg compared cognitive ability as measured at age 12 and compared it to SWB as measured at age 52 and found no connection between childhood cognitive ability and adulthood life satisfaction when controlling for childhood socioeconomic status, though they did find weak effects on satisfaction with individual life components (e.g., satisfaction with health or satisfaction with finances) (Chmiel, et al.2012).
The macro-IQ, micro-IQ paradox
A meta-analysis puts this conflicting picture in perspective. Veenhoven and Choi (2012) analyzed 19 studies and found no effect of intelligence on life satisfaction on the individual level, but analyzed four studies focused on the connection between national intelligence and national happiness and found a significant correlation, even after controlling for economic development. They speculated that this could be caused by intelligent people having higher expectations for themselves, additional uncontrolled factors beyond economic development (as controlling for economic development is tricky and other factors could be at play, like culture), or that intelligence could just add indirectly to the quality of society without impacting individuals directly.
After all, higher IQ has been connected to more efficient government institutions (Kanazawa, 2009), reduced violent crime (Bartels et al, 2010), higher levels of interpersonal cooperation (Jones, 2008), and increased trust in society (Carl and Billari, 2014). Together, these effects could create a long-run benefit for intelligence in societies, even if there is no benefit at the individual-level.
IQ and income
So if IQ perhaps doesn’t matter much for individual SWB, we could look at its affect on income (a metric we think is pretty connected to SWB and happiness). It seems intuitively plausible that a higher IQ should result in both increased job performance and increased educational ability, which results in better access to jobs and thus better income.
Some evidence does suggest this. Psacharopoulos and Velez (1992) conducted an econometric analysis in rural Columbia that found a half standard deviation change in IQ lead to a 3.5% direct change in wages. Literacy scores show a reasonably strong connection to income across thirteen developed nations, even when controlling for some non-school factors (Hanushek and Woessmann, 2008).
It is possible that those in the developing world may not see a benefit from improved IQ simply because they don’t have an opportunity to put improved IQ to use. Banerjee and Duflo (2006) found that, as we would expect, the jobs in the developing world are very different than the jobs in the developed world. Most jobs are agricultural, and the non-agricultural jobs are typically either doing general labor or sales (ibid.), which might not make use of improvements to IQ.
For example, Jolliffe (1998) found that cognitive skills raised non-farm income and total income in Ghana, but not farm income, which suggests that education may not be as helpful to the many of those focused on agricultural jobs. Additionally, Vijverberg (1999) found that the effects of education on the self-employed in Ghana were weak or nonexistent.
A similar pattern can also be found in the United States, where a large-scale study found that the returns to IQ were moderate and positive across all occupations, but were lower for manual jobs (e.g., farming) than non-manual jobs (e.g., banking) (Kuncel, Hezlett, and Ones, 2004). However, in the developed world, even manual jobs often involve operating complex machinery, so the external validity to the developing world is questionable.
IQ and education
Another area for question is how appropriate it is to control for years of education when looking at the connection between IQ and income, since IQ may easily cause more years of education, which then causes higher income. This is what Glewwe, Huang, and Park (2015) found in rural western China – a high connection between IQ and educational attainment, but no connection between cognitive skills at an earlier age and wages at a later age, after controlling for educational attainment. Boissiere, Knight, and Sabot (1985) found in Kenya and Tanzania that the return on education was moderate across both manual and non-manual workers (though higher for non-manual workers), but that the returns to reasoning ability was mostly nonexistent after (a) amount of education and (b) the presence of basic numeracy and literacy were controlled for.
Other studies find a connection between education and income too, though they don’t mention the role of IQ. Asadulah (2006) found statistically significant effects of primary education on wages in Bangladesh, especially for females and those in urban settings. Duflo (2001) found a connection between education and wage for primary education in Indonesia, but found no effect beyond age 7. Lastly, Alderman et.al.(2009) found that there was an effect of education on wage in rural Pakistan that was the result of increased cognitive ability and not the credentialism of having a degree.
One concern with this avenue, as pointed out by Behrman, Ross, and Sabot (2002), Duflo (2001) and GiveWell’s review on education, (2009), is that even if studies do establish a connection between education and income (or even IQ and income), these studies mostly focus on uncontrolled correlations and therefore exhibit a selection bias by highlighting only the participants who can access and maintain their education, which is usually indicative of other resources (e.g., sufficient family income and support) that could also, independently, promote wages and income.
This also means we must take individual context into account. Even if education in the developing world has some connection to wage, it may not have a connection for the “poorest of the poor” who are most likely to not be able to go to school, have a low quality school, or not be in a position to get a job that lets them take advantage of their education. Furthermore, these children are also most likely to be victims of malnutrition or other health problems that would keep them from gaining anything from school even if they did attend.
For these reasons, special care is needed to pay attention to the external validity of studies to the populations we may be trying to serve.
Overall, while we think it’s likely that IQ improves income in the developed world, there is not as clear as case for this in the developing world as we would like to see based on our desire for a strong strength of evidence. We’re concerned that mere observational studies of the impact of IQ may end up conflating IQ with general resources, like family finances, which can also improve educational attainment and future income. Ideally, we would like to see a randomized controlled trial that isolates the impact of improving IQ on life outcomes -- however, we have not been able to find one yet. We intend soon to write up how we assess strength of evidence, what our criteria is for how much strength of evidence is necessary, and what claims we do think have sufficient strength of evidence.
What about intellectual disability?
One aspect we did not mention is reducing the prevalence of intellectual disability. Dr. Flynn told GiveWell that “if the IQ of a population were normally distributed with a mean of 100 and a standard deviation of 15, then a four point increase in the IQ of the population would reduce the prevalence of intellectual disability from about 2.3% to 1.2%.” While the main effect of improving IQ of non-disabled children may not increase income, it is quite clear that there are sizable impacts on wages from establishing basic literacy and numeracy (Boissiere, Knight and Sabot, 1985; Hanushek and Woessmann, 2008). It’s possible that we might find impact among reducing the level of intellectual disability, however we’re still unsure about the severity of the intellectual disability that is being averted and whether it would make the difference between whether someone becomes literate and numerate or not.
One aspect we were curious about, however, was whether reducing intellectual disability had any effect on well-being directly. A survey in England found that mean overall SWB was only slightly lower among the intellectually disabled, as compared to the rest of the population (Emerson and Hatton, 2008) and similar findings were also found via a survey done in Kentucky (Sheppard-Jones, 2003). Of course, this could be wildly unrepresentative of experiences in the developing world, where culture and institutions of care can be very different than in the developed world, so we would take the effects of improving income more literally than these effects.
So does IQ matter?
Overall, we remain unconvinced that increasing IQ is as worthwhile a pursuit as other metrics, like increasing income or decreasing the burden of disease (as measured in DALYs), both of which we intend to talk about at length in the future.
We think, intuitively, it is plausible there is a connection between IQ and well-being. However, empirical studies point to the idea that this connection may only bear out on the macro-level and not on the micro-level. This makes the overall effect size of IQ-improving interventions incredibly unclear and complex to study. For example, we wouldn’t know to what degree iodization of salt contributes to improved social institutions and reduced crime, making it very difficult to form sufficiently robust cost-effectiveness estimates.
We also think it is quite possible there is a connection between IQ and income in the developing world. However, existing studies suggest that this may happen by improving educational attainment, which might not work in contexts where educational access is harder to come by. Furthermore, all the studies of IQ and income we found in the developing world are observational studies, which opens up the possibility that any observed effect of IQ is the result of the influence of uncontrolled additional variables, like family resources, that cause both increases in IQ and increases in educational attainment.
Overall, researching the impact of interventions is already hard enough without worrying about the difficulty of knowing the effect of the intermediary metric on outcomes we care about. Therefore, we remain skeptical that improvements to IQ will lead to robust, concrete beneficial outcomes for the extremely poor people that we would focus our efforts on.