What is the test for admissibility of "shaky but admissible evidence"?

"Disputes as to the strength of an expert's credentials, faults in his use of a particular methodology, or lack of textual authority for his opinion, go to the weight, not the admissibility, of his testimony." Kennedy v. Collagen Corp., 161 F.3d 1226, 1231 (9th Cir. 1998) (citation and brackets omitted). "Shaky but admissible evidence is to be attacked by cross examination, contrary evidence, and attention to the burden of proof, not exclusion." Primiano, 598 F.3d at 564.