What is the test for determining whether a business purpose is sufficiently compelling to override discrimination?

"the business purpose must be sufficiently compelling to override any (discriminatory) impact; the challenged practice must effectively carry out the business purpose it is alleged to serve; and there must be available no acceptable alternative policies or practices which would better accomplish the business purpose advanced, or accomplish it equally well with a lesser (discriminatory) impact."

Blake, supra, at 1376, quoting from Robinson v. Lorillard Corp., 444 F.2d 791, 798 (4th Cir. 1971).