In the field experiment world, we have a strange name for money grants. We call them "capital drops" - a name that invokes food aid being dropped by air in a relief zone, only we deliver cash instead of food, travel in minibuses instead of helicopters, and distribute our cash prizes randomly to eligible people instead of to the most needy. I recently completed my first "capital drop" - we distributed $10,000 in $133 grants - and based on the looks on our participants' faces, "joy drops" might be a more fitting name.

One cash winner burst into tears. Another jumped up, shouted, and ran a small lap around the market. Two people stopped to hold the envelope, with a picture of their prize inside, up to the sky and say a silent prayer before opening it. Both won cash. Almost everyone had a story about how they knew they were going to win because they did a good deed for their sister, or had a good prayer at church the week before. We had trouble finding one winner when we came to deliver the money. Turns out, she was in labor at the time. We met her at the hospital the next day - she could not have been more appreciative.

I've been getting plenty of practice with the local language, Twi, fielding "thank you" calls when they somehow find my personal phone number. I wrote the code that randomized the cash winners myself. I know it was random who won money and who didn't. But still, I can't help but smile and say "You're welcome", feeling good knowing that, whatever the impact of the capital drop may be in our study, it certainly increased joy.