‘Are you suggesting we think about switching off his respirator?’ The Consultant nodded, ‘not immediately, but yes’.

Our son was born unable to breathe. He was transferred to a specialist unit, a tracheostomy and respirator attached to his tiny body. Over the first week, they tried periodically to see if he would breathe on his own. He wouldn’t. Now we sat with the Consultant, an MRI scan of our son’s brain in hand and a grim diagnosis: even if he made it through the week, he faced a short and cruel life.

At the time I was a life-tenured professor at Cambridge University. Unable to sleep, I scoured the medical library, clinging to the hope that our Consultant was wrong; since almost no healthy newborns have MRIs, how could we really be sure our son’s was abnormal? Following up with a team at the Mayo Clinic confirmed that hope: it didn’t mean that our son would be OK, but it did mean the information available to our Consultant was far from conclusive.

Suffice to say, our son is now a strapping teenager, climbing mountains, doing well at school and, frankly, a lot more sociable than me. Medics saved his life but the story serves as reminder that even the most able professionals are susceptible to mental biases.

I, for my part, am no longer a Professor. Instead I dedicate my time to building two things into government: a model of human behavior that recognizes and corrects for human miscalculation; and evidence of what really works to change the outcomes we care about.  It is my mission to build a world where policymakers question the long-held assumptions on what makes a successful public service and where experimentation is rewarded above stubborn allegiance to untested ideas.

This is also the mission of Bloomberg Philanthropies’ What Works Cities initiative; a $42 million investment providing mid-sized US cities with the opportunity to take their use of data and evidence to new heights. Over the last year, BIT has worked with What Works Cities to answer more than 20 different versions of the “what works?” question. We’ve found out how to get residents to fix blighted properties faster, ways to recover debt repayments for city services like parking and sewer billing, and how the police can attract more applicants from under-represented groups.

Sometimes the results are surprising. Ask yourself this question: which is more likely to get low income residents of New Orleans to sign up for a free doctor’s appointment; a message that tells them they’ve “been selected”, or saying “take care of yourself so you can take care of the ones you love”? Intuitively, we might expect pulling the heart-strings to be more powerful but the second message did worse than simply providing the facts. Telling people they have “been selected” – a message that emphasizes the scarcity of the opportunity and plays on the recipient’s ego – won out.

Sometimes the answer seems obvious in hindsight. Take Lexington, Kentucky, for example; sending letters with a handwritten note – “David, you really need to open this!” – on the envelope boosts the number of people paying their outstanding sewer debt 10% compared to a letter with no markings on the envelope, and by 83%  – that’s hundreds of thousands of dollars in additional revenue – compared to no letter at all. Deciding to pay a bill is not, after all, a single step process; if customers don’t open the envelope they’re not going to know they need to pay.

Sometimes we find out things that hint at bigger opportunities. In Chattanooga, a postcard that emphasized the job security and the professional challenge associated with working in the Police tripled the number of applications and was especially effective for people of color and women. With cops from the recruitment round currently in Police Academy, it’s clear that these things matter if we are to build a level playing field and represent the world we live in through our public services.

This low cost approach to evaluation is just one of the items in the modern policymaker’s toolkit.  Together with others – OpenData, analytics, and new models of commissioning, to name a few – we can build a global movement where governments make decisions based not just on inkling or good-intention, but on data and evidence.

The Bloomberg Philanthropies What Works Cities movement is already making urban America’s future brighter than ever, and I am proud to be a part of it.

If want to run your own evaluations, enroll in BIT’s What Works Cities evaluation course here.

Dr. David Halpern is the Chief Executive of the Behavioral Insights Team – a partner on Bloomberg Philanthropies’ What Works Cities initiative – and What Works National Adviser for the UK.

 Image: A sunset view of the Long Island City skyline and East River, New York City. UN Photo/JC McIlwaine.