The Social Security Administration is evaluating BOND to determine how best to help more SSDI beneficiaries return to work and earn more, thereby allowing them to take steps toward a better quality of life. The best way to evaluate a program like this one is to see how people do under BOND rules compared to how they would under current SSDI rules. To do this, the evaluation uses a kind of selection process similar to a lottery called random assignment to create several groups, some of which are allowed to use BOND's special rules, while the others are still subject to regular SSDI rules.
Because beneficiaries are assigned to the groups randomly, the only systematic difference between the groups is the difference between BOND rules and regular SSDI rules. Therefore, any systematic differences in employment and earnings between the groups can be attributed to BOND.