N.H. Rev. Stat. Ann. § 508:13

In determining whether the person against whom a malpractice claim has been made has met the applicable standard of care, the jury or judge shall not be bound or limited by the standard of care accepted or established with respect to any particular geographical area or locality, but shall consider only whether the person against whom the claim is made has acted with due care having in mind the standards and recommended practices and procedures of his profession, and the training, experience and professed degree of skill of the average practitioner of such profession, and all other relevant circumstances.