I am using the definition of "metaphysics" that is nearly synonymous with "epistemology" and related to "ontology". I am using the definition of "the basis of science" because no other word means "basis of science". (Funk and Wagnalls 1952). "Science" here means "the study of reality".
Some users of the word mean it more or less broadly such as the book "The Metaphysical Foundations of Modern Science" uses the term more broadly than I and includes such concepts as where ideas originated and how they arose. I believe most of this more accurately falls under the heading (definition) of "history" but to each his own.
Obviously you are using the term differently than I am because without understanding things like definitions and experiment design we don't really know experimental results.
That is very different than metaphysics, which is a philosophical discipline. Epistemology is one *part* of metaphysics, but so is ontology. The 'basis of science' depends on which of several different metaphysical philosophies you adopt. it isn't a single topic, nor does everyone agree on the conclusions.