What is the narrator point of view in the novel, The Invisible Heart: An Economic Romance?

For most of the book, Roberts uses a third-person perspective with Sam being the narrator. Since the chapters jump from one group to another, the point of view while a third person the narrator can change. Baldwin and Krauss both are narrators when their scenes appear. Roberts separates the scenes so there is no confusion about who is talking. Sam carries the story since he is sharing his economics theories.