In an article published in the Journal of Politics John Gerring, Strom Thacker and Rodrigo Alfaro examine the relationship between democracy and social welfare. Here’s the abstract of Democracy and Human Development [PDF]: 

Does democracy improve the quality of life for its citizens? Scholars have long assumed that it does, but recent research has called this orthodoxy into question. This article reviews this body of work, develops a series of causal pathways through which democracy might improve social welfare, and tests two hypotheses: (a) that a country’s level of democracy in a given year affects its level of human development and (b) that its stock of democracy over the past century affects its level of human development. Using infant mortality rates as a core measure of human development, we conduct a series of time-series—cross-national statistical tests of these two hypotheses. We find only slight evidence for the first proposition, but substantial support for the second. Thus, we argue that the best way to think about the relationship between democracy and development is as a time-dependent, historical phenomenon.

And a snapshot of the conclusion, which makes a rather timely call for expectation management regarding the short-term effects of democratic transitions:

The practical implications of this argument introduce grounds for both optimism and caution with respect to the ability of developing countries to improve their levels of human development. Realistically, countries should not expect large immediate dividends in human development to result from democratic transitions. On the other hand, given sufficient time, democracy should begin to yield important, tangible benefits to the underprivileged in society. In a world characterized by chronically short time horizons, the substantial political challenge is to allow democratic institutions the time necessary to realize these persistent but distal benefits. 

Such a cautious note should also resonate with some open government advocates who tend to overestimate the effects of reforms in the short term while neglecting long-term perspectives. 

Source: John Gerring, Strom C. Thacker and Rodrigo Alfaro (2012). Democracy and Human Development. The Journal of Politics, 74 , pp 1-17