Small changes in incentives cannot be expected to have large behavioral changes. Many things besides welfare parameters affect an individual's decisions about work, marriage, or childbearing. Thus, a marginal change in a welfare program does not have a large effect on these decisions. Large effects should not be confused with cost-effectiveness. Small amounts of help in searching for a job are cost-effective in getting welfare recipients into the labor market because they are very cheap, not because they result in large changes.
Individual characteristics determine the extent to which people respond to program incentives.
Labor market conditions have the greatest effect on people for whom labor market work is a viable alternative to welfare. People who are disabled, who have young children and no child care options, or who have very low labor market skills are unlikely to respond to changes in the labor market because there are no realistic labor market conditions that would make work possible. Not all welfare recipients are the same, and program changes that help the most advantaged recipients might hurt the least advantaged. In other words, what works to get the first half of welfare recipients into work may not work for the other half. Background AFDC and SSI are the two main means-tested income transfer programs in the United States.