225 Pa. Code § 702 : — RULES OF EVIDENCEOPINIONS AND EXPERT TESTIMONY — Testimony by Expert Witnesses

A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:

(a) the expert's scientific, technical, or other specialized knowledge is beyond that possessed by the average layperson;
(b) the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; and
(c) the expert's methodology is generally accepted in the relevant field.

225 Pa. Code § 702