While a passenger aboard'the M/V Náutico, Lydia Rosenfeld slipped and fell on a ceramic tile floor near the buffet bar of the vessel’s Terrace Café. She suffered a shoulder fracture and incurred medical expenses as a result of her fall. Rosenfeld brought this diversity action against the operator of the M/V Náutico, Oceania Cruises, Inc. (“Oceania”), to recover damages for her injuries. She claimed, inter *1192 alia, that Oceania negligently caused the accident by failing to provide an adequate flooring surface for the buffet area of the Terrace Café.
To prove her case, Rosenfeld offered the expert testimony of Peter Vournechis, an Australian floor-safety specialist who performed various coefficient-of-friction tests to determine the slip resistance of the M/V Nautica’s flooring surfaces. Vournechis found that, under wet conditions, the ceramic-tile surface surrounding the Terrace Café had an inadequately low coefficient of friction. Thus, he proposed to testify at trial that the flooring surface was not reasonably safe for a self-serve or bistro area, because it posed a high risk for those passing through the Café to slip and fall.
Following briefing, the district court entered a pre-trial order precluding Vournechis’s testimony. The court stated only one ground for its decision:
[Rosenfeld] ... has not established that the proposed liability expert will provide helpful analysis to the Court in understanding a matter of scientific, technical or specialized expertise. Instead, the liability expert intends to testify that the floor where plaintiff fell is unreasonably safe for its intended use. Such conclusions are properly left for the Court or jury to decide.
At trial, Rosenfeld raised the issue again, asking the district court to allow her to read Vournechis’s deposition to the jury. The court denied her oral motion. At the close of the evidence, the court instructed the jury, in relevant part, as follows:
In this case the plaintiff claims that the defendant was negligent and that such negligence was the legal cause of damage sustained by the plaintiff. Specifically, the plaintiff alleges that the injury was caused by Defendant’s failure to choose an adequate flooring surface for the area where the accident occurred. ...
In order to prevail on this claim the Plaintiff must prove both of the following facts by a preponderance of the evidence:
First: That the defendant was “negligent;” and
Second: That such negligence was a “legal cause” of damage sustained by the plaintiff.
If the evidence proves negligence on the part of the Defendant that was a legal cause of damage to the Plaintiff, you should award the Plaintiff an amount of money that will fairly and adequately compensate the Plaintiff for such damage.
Following several hours’ deliberation, the jury returned a verdict for Oceania. Rosenfeld now appeals from the district court’s orders granting Oceania’s motion to preclude the expert testimony and denying Rosenfeld’s motion for a new trial. For the following reasons, we reverse.
I. STANDARD OF REVIEW
We review the district court’s decision to exclude an expert’s testimony for an abuse of discretion,
see Kumho Tire Co., Ltd. v. Carmichael, 526
U.S. 137, 152,
II. DISCUSSION
Rosenfeld argues that the district court abused its discretion by prohibiting her
*1193
from introducing expert testimony that Oceania’s choice of flooring posed a higher danger of slip-and-fall accidents than other surface types. Oceania, however, argues that the district court’s exclusion of the testimony was proper under
United States v. Frazier,
In Frazier, we clarified that trial courts determining the admissibility of expert testimony under Federal Rule of Evidence 702 must “engage in a rigorous three-part inquiry,” considering whether:
(1) the expert is qualified to testify competently regarding the matters he intends to address; (2) the methodology by which the expert reaches his conclusions is sufficiently reliable as determined by the sort of inquiry mandated in Daubert [v. Merrell Dow Pharm., Inc.,509 U.S. 579 ,113 S.Ct. 2786 ,125 L.Ed.2d 469 (1993)]; and (3) the testimony assists the trier of fact, through the application of scientific, technical, or specialized expertise, to understand the evidence or to determine a fact in issue.
Further, “it is not the role of the district court to make ultimate conclusions as to the persuasiveness of the proffered evidence.”
Quiet Tech. DC-8, Inc. v. Hurel-Dubois UK Ltd.,
Here, the district court excluded Vournechis’s proposed testimony as unhelpful, explaining that “[s]uch conclusions are properly left for the Court or jury to decide.” In this instance, we disagree. As the court instructed the jury, Rosenfeld’s negligence claim arose from “Defendant’s [alleged] failure to choose an adequate flooring surface for the area where the accident occurred.” Rosenfeld’s principal theory of the case was that Oceania’s choice of ceramic tile flooring for the Terrace Café area was unreasonable, given Oceania’s knowledge that the area was heavily trafficked and susceptible to spills. A qualified expert who uses reliable testing methodology may testify as to the safety of a defendant’s choice of flooring, determined by the surface’s coefficient of friction.
See, e.g., Great Am. Ins. Co. v. Cutrer,
Because the jury was not allowed to consider evidence about whether the slip resistance of the flooring posed a danger to passengers aboard the
M/V Nautica,
it could not have found in Rosenfeld’s favor with regard to her main negligence theory; matters of slip resistance and surface friction are “beyond the understanding and experience of the average lay citizen.”
See United States v. Rouco,
Although the district court discussed only whether Vournechis’s testimony would be helpful to a jury, Oceania advances a number of arguments on appeal concerning the reliability of Vournechis’s methods. Specifically, Oceania argues that Vournechis’s methods failed to accurately test for wet conditions, and that his conclusions were “imprecise and unspecific” and based on “incorrect assumption[s]” about the location of Rosenfeld’s fall. However, based on the facts of this case, these arguments attack the weight and the persuasiveness of Vournechis’s testimony, not its admissibility. Oceania can raise these arguments on retrial through “ ‘vigorous cross-examination’ ” and “ ‘presentation of contrary evidence.’ ”
Quiet Tech.,
Finally, we cannot say that the district court’s error was harmless. Because Rosenfeld was not allowed to admit evidence proving the inadequacy of Oceania’s choice of flooring surface, the jury could not have found that the floor near the Terrace Café’s buffet was necessarily unsafe when wet. Consequently, the jury was not able to consider whether Oceania’s choice of ceramic-tile flooring caused Rosenfeld’s injuries. This is particularly problematic in light of the negligence instruction given to the jury that “the plaintiff alleges that the injury was caused by Defendant’s failure to choose an adequate flooring surface for the area where the accident occurred.”
Accordingly, we conclude that a new trial is warranted; Rosenfeld is entitled to submit expert testimony regarding the adequacy of Oceania’s choice of flooring surface.
REVERSED AND REMANDED.
Notes
. In
Bonner v. City of Prichard,
