217 F.3d 919 (7th Cir. 2000)
Shirley A. Lang, et al.,    Plaintiffs-Appellants,v.Kohl's Food Stores, Inc., et al.,    Defendants-Appellees.
No. 99-3377
In the  United States Court of Appeals  For the Seventh Circuit
Argued April 7, 2000Decided June 22, 2000Rehearing Denied Aug. 3, 2000.

Appeal from the United States District Court  for the Western District of Wisconsin.  No. 98-C-351-C--Barbara B. Crabb, Judge. [Copyrighted Material Omitted]
Before Bauer, Easterbrook, and Rovner,  Circuit Judges.
Easterbrook, Circuit Judge.


1
Kohl's Food  Stores, a grocery chain in Wisconsin,  operates under collective bargaining  agreements that establish wage  classifications. Jobs in the bakery and  deli departments fall into one  classification, jobs in the produce  department another. Two facts give rise  to this litigation: pay in the produce  department is higher, and workers are not  distributed uniformly by sex. Most bakery  and deli workers are women, while most  produce workers are men. Plaintiffs, a  class of women who work in the deli and  bakery departments, contend that the  difference violates both the Equal Pay  Act, 29 U.S.C. sec.206(d), and Title VII  of the Civil Rights Act of 1964. Kohl's  replies that plaintiffs are short-  sighted: employees in the produce  department are included within a pay  category called "regular clerks," most of  whom are female. That most regular clerks  in the produce department are men does  not undercut the fact that most regular  clerks store-wide are women, Kohl's  insists. The employer adds that women who  want to be regular clerks in or out of  the produce department do not face any  discrimination in hiring or transfer.  None of the class representatives applied  for transfer to the produce department or  another regular-clerk position; instead  they want higher pay for their existing  work. The ratio of wages between  "department clerks" (the jobs plaintiffs  occupy) and "regular clerks," Kohl's  insists, is a subject for collective  bargaining rather than for litigation.


2
After allowing the parties to conduct  extensive discovery, the district court  granted summary judgment for Kohl's on  the Title VII claim. The judge  exhaustively analyzed the duties of  bakery, deli, and produce workers and  concluded that plaintiffs could not  demonstrate that Kohl's explanation for  placing produce positions in the "regular  clerk" classification was a pretext for  sex discrimination. (The class includes  supervisors and argues that bakery and  deli managers do the same work as produce  managers. Because the supervisors'  arguments track those of the clerks, we  use "clerks" as a generic term to  simplify exposition.) Kohl's insisted  that produce workers exercise greater  discretion in displaying and culling  produce and that produce jobs also are  physically harder than bakery or deli  jobs. The district judge concluded:  "Plaintiffs have produced no persuasive  evidence suggesting that defendants did  not honestly believe this justification  or that it is a cover for  discrimination." Honest belief is not  enough under the Equal Pay Act, however,  because that statute (unlike Title VII)  does not require intent to discriminate.  Section 206(d)(1) provides:


3
No employer . . . shall discriminate . .  . between employees on the basis of sex  by paying wages to employees . . . at a  rate less than the rate at which he pays  wages to employees of the opposite sex .  . . for equal work on jobs the  performance of which requires equal  skill, effort, and responsibility, and  which are performed under similar working  conditions, except where such payment is  made pursuant to (i) a seniority system;  (ii) a merit system; (iii) a system which  measures earnings by quantity or quality  of production; or (iv) a differential  based on any other factor other than  sex[.]


4
The district judge concluded that two  questions under this statute could be  resolved only by trial: whether the  positions in question are "jobs the  performance of which requires equal  skill, effort, and responsibility, and  which are performed under similar working  conditions" and, if so, whether the pay  differential nonetheless is "based on any  other factor other than sex". A trial  culminated in a special verdict that  answered the equal-work question in the  negative; the jury then did not address  the "factor other than sex" defense.


5
A substantial portion of plaintiffs'  appellate brief is devoted to contending  that the district judge should not have  granted summary judgment on the TitleVII  theory. Yet it is hard to see how this  can matter, given the jury's verdict on  the Equal Pay Act theory. If (as the jury  determined) the bakery, deli, and produce  jobs are not substantially equal, then  plaintiffs can't show sex discrimination.  Title VII does not require equal wages  for comparable work, see American Nurses'  Association v. Illinois, 783 F.2d 716  (7th Cir. 1986), or even for identical  work. Identical jobs with different wages  do not violate Title VII, provided that  all employees may freely select which job  to perform. Plaintiffs' Title VII claim  thus is untenable--no matter the validity  of the jury's special verdict, which we  address below--unless Kohl's  discriminated when hiring for the  different classifications.


6
Plaintiffs make much of evidence that  until the late 1960s Kohl's not only  discouraged women from applying for  certain positions but also had sex-  segregated wage classifications. This  practice is long gone, and no vestige of  the discrimination survives. Wage  schedules were merged 31 years ago, and,  unlike the situation in Bazemore v.  Friday, 478 U.S. 385 (1986), women hired  during the discriminatory period today  receive the same wages as men hired at  the same time. What remains is the  possibility that Kohl's steered  applicants by sex or selectively offered  them transfer opportunities. Loyd v.  Phillips Brothers, Inc., 25 F.3d 518,  524-25 (7th Cir. 1994). Neither the  plaintiffs' charge of discrimination  filed with the Equal Employment  Opportunity Commission nor their  arguments to the district court contended  that Kohl's today steers women to bakery  and deli jobs, or did so at any time  within the period of limitations.  Plaintiffs disavow a steering claim but  contend that Kohl's history is  informative on the wage-discrimination  claim. The district judge did not see  how; neither do we.


7
Claims under the Equal Pay Act differ  from comparable-worth arguments because  proof that the two jobs are of the same  (or comparable) value to the employer or  society as a whole, or depend on similar  effort or education, gets the plaintiff  nowhere. To succeed under the Equal Pay  Act the plaintiff must establish that the  positions entail substantially equal  tasks, performed under similar  conditions. (The Act just says "equal,"  but it is common ground that "equal" does  not mean "identical"; otherwise the  employer could defeat an Equal Pay Act  suit by adding an inconsequential and  pointless chore to one of the jobs.  Opinions commonly use the formula  "substantially equal" to express the idea  that trivial differences do not matter.  See Fallon v. Illinois, 882 F.2d 1206,  1208 (7th Cir. 1989); Epstein v.  Secretary of the Treasury, 739 F.2d 274,  277 (7th Cir. 1984). We follow that  convention.) Kohl's provided the jury  with plenty of evidence that tasks in the  produce department differ substantially  from those performed by bakery and deli  workers. Produce workers do more heavy  lifting and must exercise judgment about  (for example) which fruit is ripe, which  should be marked down, and how the  produce should be displayed to maximize  sales. Bakery and deli workers, by  contrast, stock displays according to  more mechanical specifications and use  printed expiration dates rather than  judgment to determine when inventory  should be rotated or removed. Although a  rational jury might have disbelieved this  evidence or concluded that the  differences are too slight to matter, and  thus returned a verdict in plaintiffs'  favor, a verdict for Kohl's is  invulnerable unless spoiled by trial  error.


8
Plaintiffs contend that the exclusion of  their expert witness is such an error.  Howard Risher, a self-employed consultant  with a Ph.D. in labor relations and  economics, who teaches an undergraduate  course on human resources as an adjunct  professor at the University of  Pennsylvania, prepared a report reaching  conclusions favorable to plaintiffs.  Stripped of self-congratulatory dross,  this report is three pages long and  consists of a list of clerks' duties and  an unreasoned assertion that all three  departments' positions are "virtually  identical in terms of their basic  function and are substantially equal in  terms of skill, effort, responsibility  and working conditions." The only support  for this conclusion, however, is the  list, with entries such as "[p]reparing  products for display" and "[m]aintaining  equipment". Risher did not analyze what  the clerks do to achieve these  objectives, and the district court  concluded that a list plus a bald  assertion would not assist the trier of  fact. Fed. R. Evid. 702. Risher's  deposition was as skeletal as his report;  asked how employees at Kohl's carry out  their duties, Risher replied only with  variants on "I couldn't tell you" and "I  have no idea". Apparently Risher thinks  that job descriptions trump actual tasks,  a sorry misunderstanding of the Equal Pay  Act. See Soto v. Adams Elevator Equipment  Co., 941 F.2d 543, 548 (7th Cir. 1991);  Fallon, 882 F.2d at 1208. The district  judge's decision to prevent Risher from  testifying, far from being an abuse of  discretion, see General Electric Co. v.  Joiner, 522 U.S. 136 (1997), was  absolutely correct. Many times we have  emphasized that experts' work is  admissible only to the extent it is  reasoned, uses the methods of the  discipline, and is founded on data.  Talking off the cuff--deploying neither  data nor analysis--is not an acceptable  methodology. See, e.g., McMahon v. Bunn-  O-Matic Corp., 150 F.3d 651, 657-58 (7th  Cir. 1998); Mid-State Fertilizer Co. v.  Exchange National Bank, 877 F.2d 1333,  1339 (7th Cir. 1989).


9
Risher also prepared a supplemental  report, based on his discussion with  eight bakery or deli workers in a "focus  group." This report did little more than  parrot these women's belief that bakery  and deli duties require as much skill as  produce duties. Relaying the plaintiffs'  likely testimony is not an example of  expertise. Huey v. United Parcel Service,  Inc., 165 F.3d 1084, 1086-87 (7th Cir.  1999). The report's final paragraph,  however, says that Risher "used the  Willis job evaluation system to confirm  that the jobs would be evaluated the same  in each department" and concluded that  "the jobs would be evaluated exactly the  same". Risher does not explain how the  "Willis job evaluation system" works (or  cite published literature providing that  background), what data he used as inputs,  or what outputs were obtained. Charts  attached to the report are unintelligible  without explanation, and Risher provided  none. Readers must take everything on  faith, and that alone would be good  reason to exclude Risher's conclusion.  See Kumho Tire Co. v. Carmichael, 526  U.S. 137 (1999). The few references to  the Willis system in the legal literature  suggest that it is designed to identify  comparable worth, rather than  substantially equal tasks. See AFSCME v.  Washington, 770 F.2d 1401, 1403, 1406,  1408 (9th Cir. 1985) (Kennedy, J.)  (holding, on this ground, that Willis  evaluations are unavailing). All  plaintiffs do in response is assert that  the Willis system is "a recognized job  evaluation system" that is "widely used  by businesses"--which does nothing to  fill in the blanks of Risher's report or  demonstrate that the Willis inquiry was  relevant to this litigation.


10
Plaintiffs challenge a second  evidentiary decision, which the parties  call the "outlier ruling." Kohl's  operates stores throughout Wisconsin.  Some are much larger than others, and  size affects not only the number of  employees in each department but also the  tasks to be done. Plaintiffs sought to  compare the busiest bakery and deli jobs  with the lightest produce jobs; Kohl's  naturally would have preferred the  converse. But the judge instructed both  sides to compare the tasks of median jobs  rather than the outliers at the largest  and smallest stores. Plaintiffs contend  that this ruling prevented them from  showing that some bakery and deli jobs  are substantially equal (in lifting,  responsibility, and so on) to some  produce jobs, indeed are more taxing than  some produce jobs. As plaintiffs see  things, the Equal Pay Act requires a  person-by-person comparison rather than a  categorical one.


11
To the extent plaintiffs rely on the  proposition that employers cannot make up  arbitrary categories and insist that  these be the basis of comparison, they  get no quarrel from us (or from the  district judge). See Thompson v. Sawyer,  678 F.2d 257, 274-75 (D.C. Cir. 1982).  But Kohl's did not make up the  "department clerk" and "regular clerk"  categories for this litigation, nor did  it unilaterally decide to use the same  wage scale throughout the state; the  classifications and wages are the result  of collective bargaining. Labor  agreements frequently apply to all of an  employer's sites, and these agreements  are "factor[s] other than sex" that  explain why the pay is identical at large  and small stores even though the tasks  differ. If all plaintiffs have to go on  is the difference across stores, then  they have nothing, for this variation in  the ratio between pay and the difficulty  of employees' tasks is so obviously  unrelated to sex that Kohl's would have  been entitled to summary judgment under  sec.206(d)(1)(iv). To get anywhere,  plaintiffs had to make a categorical  comparison between "department clerk"  positions and "regular clerk" positions.  Class treatment is appropriate only if  there are common issues of fact--that is,  only if it is possible to compare all  "department clerk" positions in bakery  and deli departments with all "regular  clerk" positions in produce departments.  The district court's outlier ruling  ensured that the premise of class  certification (granted at plaintiffs'  behest) would not be subverted. It was  not an abuse of discretion.


12
Two challenges to the jury instructions  require only brief mention.


13
First, the instructions told the jury  that it must determine whether the  positions are "substantially the same"  rather than "substantially equal."  Plaintiffs express concern that the jury  would treat "same" as equivalent to  "identical," which these positions  concededly were not. But using the word  "equal" could lead to the same (an  equal?) misunderstanding. Modifying  either word with "substantially"  overcomes the problem. The phrases  "substantially the same" and  "substantially equal" are substantially  identical. The special interrogatory  forms told the jury to determine whether  the positions were "substantially the  same," and the district judge sensibly  tracked that language in the  instructions; otherwise the jury could  have been confused by a difference  between the instructions and the verdict  forms.


14
Second, plaintiffs contend that the  judge erred by telling the jury that  documentary evidence such as position  descriptions and training manuals--  evidence that plaintiffs contend shows  that bakery, deli, and produce positions  have the same tasks--"could not be  considered." An instruction saying this  would indeed be erroneous, for an  employer's manuals and descriptions are  relevant to the question what the  positions actually entail. But plaintiffs  do not identify the supposedly erroneous  instruction, and we could not find one  that tells the jury not to "consider"  paper evidence. What the judge actually  told the jury is that a decision should  not be "based upon job titles or job  descriptions" but instead depends on  "actual job duties and performance  requirements." That instruction was  absolutely correct. Training manuals and  the like were relevant only to the extent  they accurately described the actual job  duties.


15
Last but not least is plaintiffs'  contention that the district judge erred  in informing the jury that the eeoc had  found in Kohl's favor on plaintiffs'  charge of discrimination under the Equal  Pay Act. Before trial the district judge  granted a motion in limine barring Kohl's  from informing the jury about the eeoc's  decision, but the judge changed her mind  after plaintiffs' counsel told the jury  that Kohl's agreed "under pressure of  this lawsuit" to reduce the pay  differential among the departments. Kohl's replied that the "pressure" came  from its unions in collective bargaining,  not from the suit; to add oomph to this  assertion Kohl's wanted to inform the  jury that the eeoc took a dim view of  plaintiffs' chances. If even the eeoc did  not support plaintiffs, Kohl's sought to  argue, then the "pressure of this  lawsuit" could not have made a  difference. This led the district judge  to inform the jury about the eeoc's  conclusion, in this language:


16
At the time of the 1998 collective  bargaining negotiations Kohl's had a  determination from the Equal Employment  Opportunity Commission that it had not  discriminated against bakery and deli  managers and clerks on the basis of their  pay. At plaintiffs' request that the  determination by the Equal Employment  Opportunity Commission be reconsidered,  the eeoc rescinded its determination.  Before any redetermination had issued,  plaintiffs' attorney decided to proceed  with this lawsuit and therefore no  determination was ever issued thereafter  by the Equal Employment Opportunity  Commission.


17
By asserting that the "pressure of this  lawsuit" led to a change, plaintiffs'  counsel implied that the suit had merit--  and that Kohl's knew that it had merit.  Kohl's was entitled to counteract this  implication, the district judge thought,  by showing that what Kohl's knew implied  that it would prevail on the merits.


18
Many decisions by the eeoc are  superficial, little more than precursors  to right-to-sue letters. But this one was  more thorough. Here is the Commission's  own description:


19
Our equal payment investigation  considered whether or not the actual job  duties of the deli and bakery manager  positions and the deli and bakery clerk  positions were substantially equal with  respect to skill, effort, responsibility,  and working conditions as those of the  produce manager and produce clerk  positions. To that end, detailed equal  pay interviews were conducted with  various incumbents of the produce manager  and produce clerk positions. These  interviews reflected that the produce  jobs were dirtier, required more physical  lifting of greater weight, more items  with greater frequency than the deli and  bakery jobs. Moreover, the produce areas  are significantly larger than the deli  and bakery areas in terms of physical  square footage. There are far more items  in produce than in deli and bakery and  produce accounts for a greater percentage  of store sales, i.e., higher sales  volume. Produce employees are frequently  called upon to help out in other areas of  the store stocking the dairy case,  retrieving the carts, et cetera. As a  result, our investigation concluded that  the jobs in question did not meet the  required equal pay test and that they are  not substantially equal with respect to  effort, responsibility, skill or working  conditions.


20
It is understandable that plaintiffs  wanted to keep this damning passage from  the jury's eyes, and they succeeded. The  jury never learned the reasoning behind  the eeoc's decision. Why plaintiffs'  counsel, having secured a ruling  excluding even a mention of the eeoc's  bottom line, then opened the door is a  mystery. Still, plaintiffs say, the jury  should not have been told about the eeoc's  conclusion because, by the time Kohl's  agreed to reduce the pay differential to  5¢ per hour, the eeoc had rescinded its  conclusion, so that the report did not  counteract the inference for which  counsel argued.


21
After receiving the eeoc's report (and  the accompanying right-to-sue letter) in  September 1997, plaintiffs asked the eeoc  to reconsider. In December 1997 the eeoc's  District Director withdrew both the  conclusion and the right-to-sue letter  pending further review. See 29 C.F.R.  sec.1601.19(b). Before the eeoc could do  any further investigation, plaintiffs  asked for a new right-to-sue letter,  which the eeoc was obliged to issue  forthwith. 29 C.F.R. sec.1601.28.Once it  sent the right-to-sue letter, the eeoc  called off its investigation and neither  reissued the original report nor prepared  a new one. The upshot was that, when  plaintiffs filed their suit, there was no  outstanding adverse decision by the eeoc.  When she told the jury about the eeoc's  conclusion, the district judge was under  the impression that the negotiations to  which plaintiffs' counsel referred took  place before the District Director's  order in December 1997. On learning that  this was not so, the judge did not  instruct the jurors to disregard the  report (a direction that would have been  futile in any event, sort of like telling  the jurors that for the remainder of the  trial none of them was allowed to say the  word "rhinoceros" to himself).


22
Was there a significant chance that the  jury would misunderstand the significance  of the eeoc's decision, and the purpose  for which it had been used--a chance so  large that it requires reversal even  under the deferential standard used to  review a district judge's application of  Fed. R. Evid. 403? We think not.  Confusion over timing is regrettable, but  the judge can't be blamed for the error  in the opening passage of the instruction  ("At the time of the 1998 collective  bargaining negotiations Kohl's had a  determination" . . .). That language had  been drafted by the parties; the judge  used it because the parties agreed on it.  Plaintiffs deny that they "stipulated" to  the language, but no matter; they did not  object to it, and that is that. Fed. R.  Civ. P. 51.


23
Because plaintiffs sought to persuade  the jury that Kohl's recognized its  culpability, Kohl's was entitled to rebut  this contention using the best available  evidence: a decision by the eeoc that the  positions were not substantially equal.  See Paolitto v. John Brown E.&C., Inc.,  151 F.3d 60, 65-66 (2d Cir. 1998).  Decisions by public bodies do not vanish  into thin air or become un-documents when  parties ask for reconsideration or settle  their differences. See U.S. Bancorp  Mortgage Co. v. Bonner Mall Partnership,  513 U.S. 18 (1994); In re Memorial  Hospital of Iowa County, Inc., 862 F.2d  1299 (7th Cir. 1988). When negotiating  with the unions, Kohl's knew the eeoc's  view, which had been withdrawn as a  result of plaintiffs' strategy but had  not been disclaimed as erroneous. The  1998 negotiations occurred against a  background that included the eeoc's  support of Kohl's position, and this was  relevant to the strength of the inference  that Kohl's and the unions acted under  the "pressure of this lawsuit" as  plaintiffs asserted.


24
Doubtless there was a risk that the jury  would overestimate the significance of  the eeoc's ruling; this is why such  conclusions generally are not admitted  (on behalf of either side) in jury  trials. See Lathem v. Department of  Children and Youth Services, 172 F.3d  786, 791 (11th Cir. 1999). Plaintiffs  note that the jury asked a question about  the report during deliberations, implying  that the eeoc's view assumed unusual  significance. By opening the door to  disclosure, however, plaintiffs took that  risk; they could not argue as they did  and then defang the best response. See  United States v. McAnderson, 914 F.2d  934, 946 (7th Cir. 1990). Nor can they  avoid the consequence of their opening  statement by contending on appeal (as  they do) that "[w]hy Kohl's narrowed the  gap in late 1998 is entirely peripheral"  (emphasis in original). That may be, but  it was plaintiffs who injected this  subject into the case and entitled Kohl's  to supply an answer. Plaintiffs did not  argue to the district judge that the  scope of the answer was too prejudicial  and never suggested any possible response  that was less prejudicial. The district  judge protected plaintiffs' substantial  rights by excluding the eeoc's actual  language and reminding the jury that the  conclusion had been rescinded. In  response to the jury's question, the  judge reread the instruction and added  that the only issue properly under  consideration was "whether the jobs are  equal" ratherthan why Kohl's and the  union changed the pay scales in 1998. The  evidence and the instructions as a whole  ensured that the jury focused on, and  answered, the right questions. Plaintiffs  had a fair trial.

Affirmed
