Decisions when the answer is only “probably.”
Everyday apps give you one confident number — but most real choices, like when to leave for the bus, are decisions made under uncertainty.
We started from how people already ride.
Rather than invent from scratch, we built on earlier interviews and ethnographic studies of how riders weigh waiting against risk — which pointed to a handful of ways to picture uncertainty. We rebuilt those into OneBusAway, a real transit app, then refined them through think-aloud sessions and 80+ pilot runs until people read them the way we intended.
Then we tested it at scale.
408 people made real, incentivized bus-catching decisions — rewarded for good calls, penalized for waiting in the rain. Of ten ways to show uncertainty, quantile dot plots and CDFs produced the best, most consistent decisions: about 97% of the best-possible payoff, and steadily better as people learned to read them.
The takeaway: shown well, uncertainty doesn't overwhelm people — it quietly raises everyone'sdecisions, not just the experts'.