Americans with disabilities are doing worse in the job market since legislation designed to help them took effect, according to a study just released by Vocational Econometrics, a research firm in Louisville, Ky. The report, based on recent Census Bureau data, shows that since the Americans with Disabilities Act took effect in 1992, the number of unemployed disabled has grown. Whereas in 1992, 33% of disabled American men were either employed or actively seeking employment, for example, only 30% were in 1993. The number of employed disabled women also fell slightly. Says David Gibson, president of the firm that conducted the analysis: "ADA is not an affirmative action plan for the disabled. It is a law that defines how employers must accommodate disabled people once they are hired. Unfortunately, it is possible that ADA is now discouraging companies from hiring the disabled."