Family Bank held meetings to help couples open new bank accounts - either joint accounts or individual accounts. Each newly opened account was randomly allocated to the free ATM treatment group or the control group. When an opened account was randomly chosen to receive a free ATM card, respondents were informed that the Ksh 300 ATM card fee would be paid on their behalf, and that they could retrieve their card at the bank branch.
Additionally, before couples decided which accounts to open, each potential account was randomly assigned a temporary interest rate of either 0, 4, 12, or 20 percent, which expired after 6 months. Joint accounts could earn 4, 12, or 20 percent interest with equal probability while individual accounts could earn 0, 4, 12, or 20 percent interest with equal probability.