KENNEDY, J., delivered the opinion of the court, in which SILER, J., joined. MERRITT, J. (pp. 499-506), delivered a separate dissenting opinion.
OPINION
KENNEDY, Circuit Judge.Plaintiffs Nancy Robin Greenwell, individually and as Executrix of the Estate of Richard W. Greenwell appeal the district court’s denial of their Motion to Strike the Testimony of Kenneth Razak, defendant KLLM, Inc.’s accident reconstructionist, their Motion for a Directed Verdict as to Liability and their Motion for Judgment as a Matter of Law or Alternatively a New Trial. Plaintiffs request that we remand this case and order the district court to enter a judgment against the defendants on the issue of liability. In the alternative, plaintiffs request that we vacate the district court’s judgment and remand the case for a new trial, with instructions that the district court judge hold a Daubert hearing as to the admissibility of the expert testimony. Although the Plaintiffs raise many issues on appeal, the essence of this legal dispute turns on the admissibility of the testimony of Kenneth Razak, KLLM, Inc.’s accident reconstructionist. Because we believe the district court did not err in admitting the expert testimony, we AFFIRM the district court.
I. Facts and Procedural History
Plaintiffs and defendant Boatwright were involved in an auto accident on July 27, 1994 in Jefferson County, Kentucky. Plaintiffs were traveling southbound on I-265, as was Boatwright, when a collision occurred causing the plaintiffs’ pickup truck to move from the left, across the expressway, into the right hand guardrail. Defendant Boatwright’s Peterbilt truck also came to Pest on the right hand side of the road. As a result of this accident Richard Greenwell was killed, Nancy Greenwell was slightly injured, and the plaintiffs’ truck incurred major property damage. Plaintiffs filed a wrongful death and personal injury action against Boat-wright, KLLM, Inc., who had an agency agreement with Boatwright, and Callis, the owner of the Peterbilt truck.
At trial defendant KLLM, Inc., introduced the testimony of an accident recon-structionist expert, Kenneth Razak. Prior to the expert’s testimony, plaintiffs filed a Motion in Limine to exclude a videotape re-enactment of the accident and the expert’s testimony. Because defendant KLLM, Inc., chose not to offer the videotape into evidence, the district court judge did not rule on this motion. The plaintiffs renewed their objection to the expert testimony at trial. The district court judge, however, allowed the expert to testify. During the course of this testimony, plaintiffs’ counsel objected to a statement by the expert that focused on the reliability of eyewitness testimony. Although the district court judge permitted defendant Boatwright’s counsel to pursue this line of questioning, he did not. At the end of the *495evidence, plaintiffs made a Motion to Strike the Testimony of the expert and a Motion for a Directed Verdict as to Liability. Both motions were denied by the district court judge and the case was sent to the jury. The jury returned a verdict finding no liability for the defendants. Plaintiffs filed a Motion for Judgment as a Matter of Law or Alternatively a New Trial, which was denied by the district court judge. This appeal followed.
Plaintiffs raise four issues on appeal: (1) whether the district court erred to the substantial prejudice of the plaintiff when it permitted the defendant’s expert to testify as to the validity of eyewitness testimony; (2) whether the district court erred in permitting the expert’s testimony as to his findings regarding the accident; (3) whether the district court erred in denying plaintiffs’ Motions for a Directed Verdict and Judgment Notwithstanding the Verdict; (4) whether the district court abused its discretion in denying the plaintiffs’ Motion for a New Trial.
II. Discussion
The first issue that the plaintiffs raise on appeal concerns statements that the defendant’s expert made during his testimony. Plaintiffs argue that the district court erred in allowing the expert to testify as to the validity of statements made by other witnesses. This Court reviews a trial court judge’s ruling as to the admissibility of evidence for abuse of discretion. See Snyder v. Ag Trucking, Inc., 57 F.3d 484, 492 (6th Cir.1995). “A finding of abuse of discretion will be made only where the reviewing court is firmly convinced that a mistake has been made.” United States v. Williams, 952 F.2d 1504, 1518 (6th Cir.1991). Although we agree with the plaintiffs that the expert’s statements were inadmissible opinion testimony, we do not find that the admission of these statements resulted in substantial prejudice to the plaintiffs.
At trial, defendant KLLM, Inc.’s expert introduced a theory as to liability that contradicted aspects of the eyewitnesses’ testimony. During this testimony, defendant Boatwright’s counsel asked the expert to give his opinion as to the accuracy of a statement that conflicted with his analysis. The exchange was as follows:
Q: Let me ask you to assume that one person who was a witness to this accident has testified that the semi tractor being operated by Mr. Boat-wright spun in a counter clockwise direction. Based upon the analysis that you made of the damage to the vehicles and their location, do you have an opinion as to whether or not that is an accurate or inaccurate statement?
A: In evaluating eye-witness testimony, I will not charge an eyewitness with fabricating testimony. I’ll merely say that’s the best judgment of what they saw and their interpretation of what they saw within the knowledge that they have and to the extent it’s a" sincere statement on their part. But I also have to observe that an event which takes place in a few seconds, only a certain type of recollection can exist of any person trying to witness, trying to recall an event that takes place in a short time.
Plaintiffs counsel: Your Honor, this witness is not being responsive to this question at all. He’s definitely not qualified to recollect events of people unless he’s some kind of mental therapist or psychologist or psychiatrist. It’s obviously not being responsive to the question.
The Court: I think he’s getting to it. Witness: May I hear the question again, please.
Q: Sure. Let’s go with based upon the analysis that you made and all of the information you gathered, do you have an opinion on the basis of scientific probability as to whether *496or not Mr. Boatwright’s semi tractor when it spun, spun in a counter clockwise direction to cause this accident as opposed to some other direction after the accident.
A: I have an opinion on that point.
Q: And what is that opinion?
A: That the spin out of the truck was induced after the contact between the truck and pickup. That it was in a clockwise direction.
Q: Why do you say it was a clockwise direction?
A: Two reasons: Number one, the physical facts, particularly the way the tractor came up to and collided with the guardrail at Exit 25. The way it collided with the sign at Exit 25 damage to the truck, and the gaging in the grass and throwing of dirt onto the pavement of the Gene Snyder Freeway. All of those could have occurred only if the truck were spinning in a clockwise manner viewed from above. Those are the physical facts.
(J.A. 648-49).
Plaintiffs’ counsel objected to the expert’s response commenting on the credibility of eyewitness testimony as non-responsive, but did not move to strike the testimony. The district court judge permitted the response.
Plaintiffs argue that the expert's testimony as to the credibility of eyewitness testimony was beyond the scope of his expertise. Defendants contend that this testimony was not intended to discredit the eyewitnesses’ testimony, but rather was intended only to explain the expert’s reasons for basing his theory on physical evidence, rather than the testimony of the eyewitnesses. Regardless of the intent or motivation of the expert in commenting on the eyewitness testimony, we agree with the plaintiffs that the testimony regarding the credibility of eyewitness testimony was improper; however, we also believe that the admission of this testimony amounts to harmless error.
In assessing whether this opinion testimony resulted in substantial prejudice to the plaintiffs, we must consider the statement in the context of the expert’s entire testimony. After plaintiffs’ objection to the testimony, the defendants did not pursue the line of questioning further. In the ninety-five recorded pages of the expert’s testimony, this statement is the only one addressing the credibility of the other witnesses. In addition, plaintiffs were permitted to challenge all of the expert’s testimony on cross-examination. Although the district- court judge did not sustain the plaintiffs’ objection as to these statements, the judge did provide proper instructions to the jury in assessing the expert’s testimony. At the conclusion of evidence, the district court judge advised the jury that it was to weigh the credibility of each witness and if it determined that the expert’s opinion was entitled to no weight, the jury could disregard the expert’s testimony entirely. Given these facts, it is beyond the purview of this Court to find that the admission of this evidence caused substantial prejudice to the plaintiffs.
The second issue the plaintiffs raise on this appeal is that the district court erred in permitting the expert to testify without first conducting a Daubert hearing. In Daubert, the Supreme Court held that trial judges were required to make an initial determination “of whether the reasoning or methodology underlying the testimony is scientifically valid and of whether that reasoning or methodology properly can be applied to the facts in issue.” Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 592-93, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993). This two step inquiry requires the trial judge to assess the relevance and the reliability of the expert’s testimony. The relevance requirement ensures that there is a “fit” between the testimony and the issue to be resolved by the trial. See United States v. Bonds, 12 F.3d 540, 555 (6th Cir.1993). The reliabili*497ty requirement is designed to focus on the methodology and principles underlying the testimony. See id. at 556.
Plaintiffs’ arguments against the admissibility of the expert testimony focus on the second inquiry of the Daubert test — reliability. Because the expert’s theory of the accident contradicts the testimony of the eyewitnesses plaintiffs contend that the testimony is inadmissible. Yet, the plaintiffs did not challenge the expert’s credentials as to accident reconstruction. They also did not challenge the scientific formulas the expert used in making his determination of how the accident occurred. In addition, plaintiffs did not contend that the physical evidence the expert used was inadmissible. Rather, the plaintiffs challenge the conclusions that the expert reached as to the cause of the accident. In particular, the plaintiffs fault the expert for not incorporating the testimony of the eyewitnesses into his theory of the accident.
The purpose of a Daubert hearing is to determine “the scientific validity and thus the evidentiary relevance and reliability— of the principles that underlie a proposed submission.” 509 U.S. at 594-95, 113 S.Ct. 2786. “[T]he Daubert Court has instructed the courts that they are not to be concerned with the reliability of the conclusions generated by valid methods, principles and reasoning.... If the principles, methodology and reasoning are scientifically valid then it follows that the inferences, assertions and conclusions derived therefrom are scientifically valid as well.” Bonds, 12 F.3d at 556. In this case, the only issue to be resolved by a Daubert hearing is whether it was scientifically valid for the defendant’s expert to base his theory solely on the physical evidence obtained from the accident. The expert proffered a legitimate explanation for his decision to disregard the eyewitnesses’ testimony in reaching his conclusion. He stated that the eyewitness testimony was contradictory and that he had no principled basis for accepting one eyewitness version of events over another; thus, he disregarded all of them.
A review of the record shows that the expert was correct in stating that the eyewitness testimony did contradict one another. In fact, two of the eyewitnesses claim to have been in the same location behind the Peterbilt truck when the accident occurred.1 The difference between the expert’s testimony and the eyewitnesses’ testimony goes to the conclusion that each witness reached as to the cause of the accident. Expert testimony is not inadmissible simply because it contradicts eyewitness testimony. Expert testimony, however, is inadmissible when the facts upon which the expert bases his testimony contradict the evidence. See United States v. Chaney, 577 F.2d 433, 435 (7th Cir.1978).
Plaintiffs do not challenge the factual basis of the expert’s testimony — the physical evidence — instead, they challenge the *498inferences made by the expert and the jury from that evidence. The testimony cannot be excluded on these grounds. Plaintiffs do not identify any factual assumptions by the expert that contradict the evidence. The expert’s testimony was based on the facts conveyed by the physical evidence. Because the factual underpinnings of the expert’s testimony were sound, his testimony is admissible.
For plaintiffs to succeed on this issue, they would have had to present facts that plainly contradict the physical evidence upon which the expert based his theory of the accident. The plaintiffs did not present facts contradicting the physical evidence; however, they now argue that the expert’s testimony was inadmissible because it contradicted judicial admissions made by defendant Boatwright. Judicial admissions of fact preclude the introduction of contradictory evidence as to the admitted facts. See Ferguson v. Neighborhood Hous. Serv. of Cleveland, Inc., 780 F.2d 549, 550-51 (6th Cir.1986). We find that Boatwright’s statements do not constitute judicial admissions.
Statements become judicial admissions only when they are “deliberate, clear and unambiguous.” MacDonald v. General Motors Corp., 110 F.3d 337, 340 (6th Cir.1997). The alleged judicial admissions by Boatwright cannot be said to be “deliberate, clear and unambiguous” waivers of his right to contest the facts. Plaintiffs contend that Boatwright admitted he lost control of his vehicle. This alleged admission conflicts with the expert’s reconstruction of the accident. Yet, Boatwright only stated that he lost braking control, he never conceded that he lost steering control. Boatwright’s statements about his control over his vehicle are not unambiguous or clear; thus, they are not judicial admissions. Plaintiffs also point to Boat-wright’s statement that he was driving too fast to exit the expressway. The expert testified that Boatwright was incorrect about his ability to have exited the expressway at the speed he was traveling— which the expert found to be greater than Boatwright had estimated. This is a statement of opinion, not fact. “Judicial admissions, ..., typically concern only matters of fact.” Id. at 341. Because Boatwright’s statements are not judicial admissions the district court did not err in admitting evidence that contradicted these statements.
Although the trial court is not required to hold an actual hearing to comply with Daubert, the court is required to make an initial assessment of the relevance and reliability of the expert testimony. Because the district court did not hold a Daubert hearing we must review the record to determine whether the district court erred in its assessment of the relevance and reliability of the expert testimony. The plaintiffs have not proffered any basis for questioning the scientific validity of the expert’s testimony, nor have they raised any issues as to its relevancy. We find that this testimony satisfies the two prong test of Daubert and was properly admitted by the district court.
The third issue the plaintiffs raise on appeal is that the district court erred by not granting their motion for judgment as a matter of law. We review a trial judge’s denial of a motion for judgment as a matter of law de novo. See Smelser v. Norfolk S. Ry. Co., 105 F.3d 299, 306 (6th Cir.1997). In order for the plaintiffs to succeed on this issue, they must demonstrate that there was insufficient evidence to raise a question of fact for the jury. See Powers v. Bayliner Marine Corp., 83 F.3d 789, 796 (6th Cir.1996). Ajs we review the evidence, we must make all reasonable inferences in the light most favorable to the non-moving party. See id. “Only when it is clear that reasonable people could come to but one conclusion from the evidence should a court grant a motion for directed verdict.” Wayne v. Village of Sebring, 36 F.3d 517, 525 (6th Cir.1994).
A ruling in favor of the plaintiffs on this issue would require us to find that the defendants offered no credible evi*499dence contesting the plaintiffs’ theory of liability. As stated above, however, we have determined that the district court properly admitted the expert testimony because it was grounded in facts based on the physical evidence. Because this evidence could be accepted by the jury as credible it raises a question of fact for the jury. For this reason, we find that the district court did not err in denying plaintiffs’ motion for a judgment as a matter of law.
The final issue that the plaintiffs raise on this appeal concerns the district court’s denial of the plaintiffs’ motion for a new trial. Our standard of review for this motion is abuse of discretion. See Powers, 83 F.3d at 796. “Abuse of discretion is defined as a definite and firm conviction that the trial court committed a clear error of judgment.” Id. A trial judge should deny a motion for a new trial if the jury verdict is reasonable. See id. Again, plaintiffs’ argument in support of this motion is based on the inadmissibility of the defendant’s expert testimony. Because we find this testimony to be properly admitted we believe that the district court did not abuse its discretion in denying the plaintiffs’ motion for a new trial.
III. Conclusion
For the foregoing reasons, we AFFIRM the district court’s judgment dismissing all claims against the defendants.
. The dissent holds that the expert's testimony lacks foundation because it fails to take into account the testimony of the eyewitnesses. The eyewitness testimony, however, is contradictory. One eyewitness contended that the Peterbilt truck was traveling with its trailer attached, while the other eyewitnesses stated that the Peterbilt truck was "bob-tailing.” This same witness, who was traveling in the left lane, did not see either the pick-up truck in front of her or the two other cars in the right lane behind the Peterbilt truck. In addition, the two witnesses who claim to be traveling in the right lane report different locations of the Peterbilt truck. One witness stated that the Peterbilt truck was already traveling on the expressway as she merged immediately behind it from 1-64. The other witness stated that the Peterbilt truck merged from 1-64 onto the expressway immediately in front of her. Although the dissent contends that the expert should have taken into account this testimony in formulating his opinion, the dissent offers no methodology for reconciling these contradictions. The dissent also argues that the expert should have considered alternative possibilities for how the accident occurred. The expert, however, did consider the dissent’s proffered explanation for the accident and found that it was not consistent with the damage to the vehicles and their ultimate location.