What is the test for making a disparate impact claim?

6 Once a relevant proxy pool is established, it must be shown with particularity that an employment practice has a disparate impact on the members of the pool. For example, in New York City Transit Authority v. Beazer, 440 U.S. 568, 99 S.Ct. 1355, 59 L.Ed.2d 587 (1979), disparate impact plaintiffs argued that the employer's refusal to hire methadone addicts had a disparate impact on blacks and Hispanics. In support of this charge, the plaintiffs introduced evidence that 63% of the persons on publicly funded methadone programs were black or Hispanic. Id. at 585, 99 S.Ct. at 1365. This was not a competent showing of disparate impact because it failed to consider both the ethnic makeup of methadone users involved in private programs and the percentage of methadone users who are otherwise unqualified for employment by reason of use of alcohol or drugs other than methadone. Id. at 585-86, 99 S.Ct. at 1365-66.