What distinguishes a non-experimental study from an experimental study?

Hello, you did not show the text to which this question refers, which makes it impossible to answer it accurately. However, if an author wants to offer information about Macarthism without offering opinions to the reader, the option that must be made is "by presenting only the facts that support a particular view of the era."

This allows the author to explain what was happening, to present important points about Macarthism, to show how it fit into the community, without presenting any opinion, but maintaining the reader's understanding.