In the early days of the Behavioural Insights Team (aka The Nudge Unit), their successes quickly became part of the behavioural economics canon. They were the only behavioural team publishing results publicly, so those became the stories everyone told. These stories included how adding social norms to tax letters increased on-time submission, giving sweets and a personalised message from the CEO tripled charitable giving rates, and messages crafted around reciprocity and fairness would boost ...