They measured the outcomes of cash transfers by asking them tons of questions about their happiness and their increase in assets a year later. Happiness questions include things like "how often in the last week have you felt hopeless?"; "How often in the last week have you felt happy?"; "How would you rate your satisfaction with life as whole?". It increased their happiness (which I think as a utilitarian is the most important outcome) as well as increased their assets a year later.

Deworming has also been found to impact income many years later. And increasing income is just another way of saying pulling out of poverty, albeit incrementally.

The question of getting to root causes is appealing and I used to be interested in this but the unfortunate truth of the matter is that nobody really has the answer. Economics is insanely complicated. In studies where you retroactively see whether economists predictions came true, the economists didn't do better than chance. So given that we don't know the root cause, but we do have interventions that provide long-lasting effects, we should focus on those.