Millions of ultra-poor households in sub-Saharan Africa rely exclusively on savings groups to meet their financial needs. However, the ability of savings groups to fully meet these needs remains unclear. We randomly assign ultra-poor Ugandan households to savings groups containing different proportions of ultra-poor members. We find evidence that groups may be unable to satisfy the borrowing ne...

The rapid increase of wealth inequality in the past few decades is a most disturbing social and economic issue of our time. In order to control, and even reverse that surge, its origin and underlying mechanisms should be revealed. One of the challenges in studying these mechanisms is to incorporate realistic individual dynamics in the population level in a self-consistent manner. Our theoretica...

Good health is not something we can buy. However, it can be an extremely valuable savings account.

We focus on automatic strategies to optimize life cycle savings and investment. Classical optimal savings theory establishes that, given the level of risk aversion, a saver would keep the same relative amount invested in risky assets at any given time. We show that, when optimizing lifecycle investment, performance and risk assessment have to take into account the investor's risk aversion and t...

Since July 1, 2007, New Zealanders have had a new option for their retirement savings―KiwiSaver―a type of subsidized, defined contribution retirement savings plan offered by private-sector providers. New labor force entrants in permanent positions who are aged 18 or older are automatically enrolled in a KiwiSaver plan, but are able to opt out of the plan if they wish. Also, all individuals youn...

We establish cancellation in short sums of certain special trace functions over $${\mathbb {F}}_q[u]$$ below the Pólya–Vinogradov range, with savings approaching square-root as q grows. This is used to resolve -analog Chowla’s conjecture on Möbius polynomial sequences, and Bateman–Horn degree 2, for some values q. A final application primes .