Alexander Krauss writes on the topic:
The existing literature is laden with contradictory hypotheses and findings that suggest this potential relationship can be positive or negative, stronger or weaker, differentiated or non-existent and can vary across and within countries and time periods. However, fundamental methodological and empirical limitations of analysis do not allow us to make such claims robustly, to some extent because the process of democratisation and changes in levels of equality are highly nuanced, idiosyncratic and heterogeneous and thus difficult to capture econometrically. Some of the most prominent authors in this literature claim that high levels of inequality decrease the likelihood of democratisation, and they also talk about “causal effects” and “the impact of democracy” on outcomes. Such conclusions presuppose a number of very demanding assumptions and requisite premises that cannot be rigorously met.
In fact, thousands of academic papers analyse the potential relationship between political variables like democracy and economic variables like inequality by gathering their data, selecting their methods and then going forward with their analysis, interpreting their findings and potentially informing policy, with many other steps along the way that involve making important implicit methodological assumptions. My recent paper1 instead goes backwards to analyse whether the data and methods that are applied by the leading authors in this literature are able to produce the robust results that they claim. It emphasises that how we as researchers generate our correlational (or ‘causal’) claims cannot be viewed independently from how we make everyday, typically unreflective decisions, such as what we decide to analyse, how we construct our variables, how we collect and use our data, which methods we choose to apply, how we interpret our statistical results, and so forth.
Many a times just a narrative account which sums up all the arguments for and against is more useful than the several empirical jazzes which goes around. But you can no more publish anything narrative, so the game continues..