632.2 Extent of disparity

A disparate impact analysis must include a conclusion as to whether the degree of disparity between the protected class and the non-protected class is of sufficient magnitude to establish a prima facie case for disparate impact, and a Complainant must prove that its disparity figures are statistically accurate to the degree (called a “confidence level”) required by law. Where demonstration of statistically significant disparate impact is concerned, the Department is unwilling to intuit what ought to be demonstrated by expert opinion. Popp v. Rhinelander Paper Co. (LIRC, 07/28/95).

Disproportionality of a distribution of minorities in a particular employment setting is proven in disparate impact cases almost exclusively by some kind of expert statistical analysis. A Complainant's intuitive sense that a minority's distribution in a seniority system must have a negative impact on their opportunity for advancement cannot substitute for the kind of rigorous statistical analysis that is necessary to establish a claim of disparate impact in promotion. Moncrief v. Gardner Baking (LIRC, 07/01/92).

The 4/5ths Rule is not a sophisticated enough statistical test that it should be relied on to establish that there has been discrimination, but it is useful in identifying cases where the evidence is so weak that discrimination can be ruled out. Under the 4/5ths Rule, a disparate impact will ordinarily not be inferred unless the rate at which a protected group is successful in a given situation is less than 4/5ths of the rate at which others are successful. Helton v. Wesbar Corp. (LIRC, 03/19/92).

A disparate impact analysis must include a conclusion as to whether the degree of disparity between the protected class and the non-protected class is of sufficient magnitude to establish a prima facie case for disparate impact. In addition, the Complainant must prove its disparity figures are statistically accurate to the degree, called a “confidence level,” required by law. Racine Unified Sch. Dist. v. LIRC, 164 Wis. 2d 567, 476 N.W.2d 707 (Ct. App. 1991).

The “4/5ths rule” in EEOC guidelines (i.e., that adverse impact will not be inferred unless the members of a protected class are selected at a rate less than 4/5ths of the rate at which the group with the highest rate is selected) is not a rule that presumes that discrimination has occurred where its conditions have been met. There are more reliable statistical tests than the 4/5ths rule. Watson v. WPS (LIRC, 09/06/89).

The fact that the percentage of a protected group in a particular job category is relatively small is not significant unless there is relevant statistical evidence concerning the qualified, available labor pool for that job and the percentage of employees in the protected group is less than the percentage of that group in the available labor pool. Chandler v. UW-La Crosse (Wis. Pers. Comm’n, 08/24/89).

A company’s hiring policies did not disproportionately impact on black applicants where statistics presented could not lead to a reasonable inference that they were not excluded at a rate substantially higher than white applicants and where the company hires blacks at a rate double their representation in the relevant labor market. Nickols v. LIRC (Milwaukee Co. Cir. Ct., 12/03/82).

A Complainant failed to establish disparate impact where, using a binomial model, the standard deviation arrived at did not show that women as a class were being hired or promoted at a significantly lower rate than men. Niles v. Delco Electronics (LIRC, 10/22/82).

To prove that a test or procedure has a disparate impact, a job applicant must show that it selects persons of a particular national origin in a pattern significantly different from the pool of applicants in general. A Hispanic applicant for a summer job program failed to meet this burden where she was the only Hispanic to apply and was one of 27 other applicants who were rejected in the initial screening process. Sanchez v. LIRC (Dane County) (Dane Co. Cir. Ct., 11/20/80).

A female applicant failed to establish a prima facie case that the employer’s recruiting practice of advertising a math position combined with a wrestling coach position had a statistically significant adverse impact on women. Marcoux v. DeForest Joint Sch. Dist. No. 10 (LIRC, 09/25/80).