of the evidence.”); Barrett v. Rhodia, Inc., 606 F.3d 975, 980 (8th Cir.2010) (“[T]he party offering the expert testimony “must show by a preponderance of the evidence both that the expert is qualified to render the opinion and that the methodology underlying his conclusions is scientifically valid.” ” (internal citations and quotation marks omitted)); accord Baker v. Urban Outfitters, Inc., 254 F.Supp.2d 346, 353 (S.D.N.Y.2003). “The district court is the ultimate ‘gatekeeper,’ ” United States v. Williams, 506 F.3d 151, 160 (2d Cir.2007), and must ensure that “any and all scientific testimony or evidence admitted is not only relevant, but reliable,” Daubert, 509 U.S. at 589, 113 S.Ct. 2786; see Kumho Tire Co. v. Carmichael, 526 U.S. 137, 152, 119 S.Ct. 1167, 143 L.Ed.2d 238 (1999) (<HOLDING>); Nimely v. City of New York, 414 F.3d 381, 396
holding that whether the witnesss area of expertise was technical scientific or more generally experiencebased the court in its gatekeeping function must make certain that an expert whether basing testimony upon professional studies or personal experience employs in the courtroom the same level of intellectual rigor that characterizes the practice of an expert in the relevant field holding that in some cases the relevant reliability concerns may focus upon personal knowledge or experience and that the trial judge must have considerable leeway in deciding  how to go about determining whether particular expert testimony is reliable holding that the basic gatekeeping obligation of daubert applies to all expert testimony holding that an expert witnesss testimony on an ultimate issue was admissible recognizing that the expert did not specifically testify that the defendant was guilty or that as a matter of law the facts satisfied the applicable legal standard holding based on legislative history and statutory construction principles that the statute does not require that expert be in same field of practice only a field involving the same type of care or treatment