What Criteria Do You Use to Distinguish between Knowledge, Opinion and Propaganda?

Title: "There are many different authorities, including academics, politicians, global organizations and companies, who make knowledge claims. As an experienced TOK student, what criteria do you use to distinguish between knowledge, opinion and propaganda?"
Introduction
These days, in the information age of the 21st century people in our society are engulfed in the mass media and receive many kinds of information. All this abundance of information raises fundamental questions on information its self. How much information and of what value do we get every day, from either seeing something, being taught in school or just watching TV? From all the opinions and propaganda we are exposed to every day, how much of that has turned into our knowledge? In what way has our knowledge, with the help of propaganda formed our opinion?
Hypothesis
I believe that the criteria for distinguishing between knowledge, opinion and propaganda are:
1) To analyze what type of people, in terms of cultural, historical and educational background believe in a certain issue.
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