What is the burden of meeting a listed impairment?

To meet a listed impairment, plaintiff bears the burden of establishing that she meets each characteristic of a listed impairment relevant to her claim. See Burch v. Barnhart, 400 F.3d 676, 683 (9th Cir. 2005). To equal a listed impairment, a claimant must establish symptoms, signs and laboratory findings "at least equal in severity and duration" to the characteristics of a relevant listed impairment, or, if a claimant's impairment is not listed, then to the listed impairment "most like" the claimant's impairment. 20 C.F.R. 416.926. A finding of equivalence must be based on medical evidence only. 20 C.F.R. 416.929(d)(3).