inputs: hypothesis: The first two borrowers must start repaying the principal plus interest over a six-week period. premise: The borrowers must form five-member groups that, along with the bank's field workers, closely supervise the loans. Peer pressure substitutes for collateral because the group's first two borrowers have to start repaying the principal plus interest over a six-week period before the other members can take out loans. The interest rate is fixed at 16 percent.