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Evaluating claims you find on web sites: Introduction

What is a credible source: a checklist

How to use this guide


Imagine that you are writing a paper.  You find an interesting claim (a fact or assertion) on the Web. Before you insert this claim into your paper, you need to evaluate how credible its source is. Can you trust the web site to get it right?

This guide will help. Use it like a checklist.  Start on this page, then visit the other tabs in order:

  • A) The Claim
  • B) Authority
  • C) Bias
  • D) Publication Type

Each tab has two parts.

  1. Read the introduction.
  2. Then proceed through the questions.


Continue below.

What is a credible claim? What is a credible source? How I know what to trust?

To answer many questions, we simply need to make observations and use common sense.

  • Does my car have enough gas to get to Phoenix?
  • How did the dog get loose again?

But for other questions, even in our personal lives, we need to trust the knowledge of other people.

  • Why is my car shaking at highway speed?
  • Does my sick dog need an operation?  What are the chances of success?

For academic questions, we have to rely on experts for facts and for interpretation of the facts.

  • Will the world population peak at 10 billion?
  • In World War II, did Japan surrender because the U.S. used atomic weapons, or were other reasons more important?

Whenever we cite claims made by others, we need to consider the credibility of these sources.  

A credible source is one that has a high probability of making true claims.

To test the credibility of a claim made by a source, consider the following questions:

A)   The Claim:

Do you understand the claim? Is it plausible on its face? Is it relevant to your argument?

B)  The Authority of the source:

Are the authors in a good position to know the truth of the claim? Do they have relevant expertise? Have they studied the relevant data?

C)  The Bias of the source:

Okay, so the authors may be experts, but can we trust them to give us the straight story? Could the authors' bias have distorted the truth in this document? Could they have misled us, consciously or unconsciously?

D)  The Publication type of the source:

Does the publishing process for this source "build-in" some quality control? Does it increase our trust?

Go to the next tab: The Claim.