In data on 275,000 Americans and a survey of 3,505 more, people whose politics differ from their area’s average were less likely to donate blood, a drop of about 20% from the baseline odds. Racial diversity showed no such effect.

Across 11 experiments with 12,688 participants, telling people they could join a short streak of donors raised giving more than telling them a high percentage of others had donated, because streaks made people feel their gift would influence the next person.

Tracking Uber’s rollout across 323 US metro areas from 2013 to 2018, an economist found its arrival cut local unemployment by between a fifth and a half of a percentage point, about a 3.2% drop, with a small lift for low-end wages.

An analysis of Final Jeopardy wagers from 1,669 recent episodes and 492 episodes from the 1980s found no sign that female contestants are more risk averse than male ones, in either era.

In four experiments, narcissistic job seekers rated postings full of “Rule-Bender” phrases such as “thinks outside the box” and “results-oriented” as a better fit, and professional recruiters reached for that language more for high-growth firms and when aggressive financial reporting would pay off.

Tracking tens of millions of Americans in census records from 1850 to 1940, economists found that 72% of the top 1% fell out of it within ten years, and 93% of grandchildren of top 1% grandfathers never reached it themselves.

Pooling 32 studies with 256 effect sizes, a meta-analysis found vacations have a large effect on employee well-being that fades more slowly than earlier work suggested; switching off from work and staying physically active helped most.

Using Facebook data, researchers found that boys who are relatively old for their school cohort make 11% more friends in high school, are 42% more likely to become class president, and as men have bigger networks and more often go into management and entrepreneurship.