I’m doing some research work at the moment on a certain country, and have identified a negative relationship between inequality (measured using the Gini index) and all-cause mortality. I’m not at liberty to identify the country, or the details, of course. This negative relationship means, in essence, that the more unequal a small area becomes, the lower the death rate in that area. The effect is very very weak, so essentially can be dismissed as a policy concern (other aspects of the area’s economy drive much greater increases or reductions in mortality).
Typically, when a result like this occurs, people will dismiss it as either a statistical oddity or will say that the inequality effect is operating as a proxy for other phenomena – for example, the observed values of inequality measure the effect of past rapid economic growth, or are a proxy for some other aspect of the economy or society (social capital, corruption, etc.). The reason for this is simple: it’s very hard to construct a mechanism by which increasing inequality can reduce mortality, but it’s easy to say that inequality increases as wealth does, and that increasing wealth reduces mortality (a fairly solid fact). There is a model for how inequality can increase mortality, through mechanisms such as reduced social welfare support, or inability to seize necessary cultural or physical capital – there are quite a few convoluted mechanisms proposed by which relative inequality can have this effect in wealthy countries like the UK.
I’m a realist in this regard, and I don’t think relative inequality is important to health – I think it’s absolute inequality that determines health, in the vast majority of cases – thus in the short term development is more important than equality (or, in many cases, basic rights – see e.g. China). But this data I’m playing with measures relative inequality – that is, it measures the distribution of wealth, and looks at the relationship between this distribution and mortality after adjusting for absolute wealth (how rich an area is).
So, here’s a challenge to my reader(s): can you propose a social mechanism by which increased relative inequality reduces mortality? This mechanism needs to work across regions with a diverse range of income levels and other forms of social determinants of health. Imagine it in your own country, if you like: whether you’re living in Sao Paulo or on the edge of the Amazon, greater disparity in wealth will reduce mortality. Can you explain how this happens without falling back on arguments that a) the measure of inequality is a proxy for something else or b) higher absolute wealth generates higher relative inequality.
Have at it, if you dare!