ordinarily engage in a searching inquiry into whether the expert’s methodology satisfies the Daubert factors of evidentiary reliability. This is no less true in product liability actions where the proposed expert is an engineer who offers to testify about an alleged defect in a product’s design or manufacture. See, e.g., Cummins v. Lyle Indus., 93 F.3d 362, 367-368 (7th Cir. 1996); Deimer v. Cincinnati Sub-Zero Prods., Inc., 58 F.3d 341, 344-345 (7th Cir. 1995); see also Tyus v. Urban Search Management, 102 F.3d 256, 263 (7th Cir. 1996), cert. denied, 117 S. Ct. 2409 (1997).
The Daubert factors also apply with equal force in cases where an expert eschews reliance on any rigorous methodology and purports to base his opinion on “experience” or “training.” See, e.g., Cummins, 93 F.3d at 368 n.2; note 4, supra.12/ “[N]othing in either Daubert or the Federal Rules of Evidence requires a district court to admit opinion evidence which is connected to existing data only by the ipse dixit of the expert.” Joiner, 118 S. Ct. at 519. Instead, a district court is required to rule out “‘subjective belief or unsupported speculation’” by considering “whether the testimony has been subjected to the scientific method.” Wintz, 110 F.3d at 512. Either “hands-on testing” or “review of experimental, statistical, or other scientific data generated by others in the field” may suffice. Cummins, 93 F.3d at 368.
Applying these settled principles of Seventh Circuit law, the district court granted defendants’ motion to strike the opinions of James Lafferty concerning two subjects: (1) whether Clark’s lap belt became unbuckled during the accident; and (2) whether the lap belt had blood on it (and, if not, the significance of the absence of blood). As we next
12/ Indeed, “it seems exactly backwards that experts who purport to rely on general engineering principles and practical experiencemight escape screening by the district court simply by stating that their conclusions were not reached by any particular method or technique. The moral of this approach would be, the less factual support for an expert’s opinion,the better.” Watkins v. Telsmith, Inc. 121 F.3d 984, 991 (5th Cir. 1997).