How to Evaluate Online Sources

Your professor just commented: “This is not a credible source.” A research paper is only as strong as its sources. Using weak, biased, or non-academic sources leads to a low grade.

This guide is your resource for how to evaluate online sources. We teach what academic sources are, where to find them, and how to evaluate them. Knowing how to *find* sources is half the battle. Our guide to finding credible sources can get you started, but this page is the next step: evaluation.

What is Source Evaluation?

Source evaluation is the critical process of determining a source’s authority, accuracy, and purpose. It’s an analysis of who wrote it, why, how they got their information, and when. This skill is the foundation of academic work, from a simple essay outline to a full dissertation. It’s how you become a critical thinker.

Peer Review: The Gold Standard

The “gold standard” for credibility is peer review. As research explains, this is a system where, before an article is published, it is sent to other field experts. These anonymous “peers” review the methodology, data, and conclusions. They check for errors and bias. If a source is peer-reviewed, you can trust it is accurate.

Primary vs. Secondary Sources

You must also know the source type you need:

• Primary Sources: Raw, original data or “first-hand” accounts. Examples: Diaries, letters, interviews, raw survey data, historical documents (like the Constitution).
• Secondary Sources: Analysis or interpretation of primary sources. Examples: Textbooks, journal articles, and scholarly books that *analyze* a historical event or experiment.

Most research papers use a mix of both.

How to Evaluate Sources (5 Steps)

Follow this process to find sources your professor will accept. This 5-step process is the foundation of the “CRAAP Test.”

Who wrote this? Who published it? An anonymous blog post has no authority. A journal article by a Ph.D. has authority. Look for author credentials and publisher reputation (e.g., University Press vs. unknown publisher).

Why does this source exist? Is its purpose to inform, to persuade, or to sell?

• To Inform (Good): Objective, neutral tone (e.g., .gov sites, academic journals).
• To Persuade (Use with Caution): Biased, uses emotional language (e.g., political or advocacy sites).
• To Sell (Avoid): A .com site that is ultimately trying to sell you a product.

Is the information supported by evidence? A credible source will cite *its* sources. Look for a bibliography, references, or footnotes. If a source makes big claims with no evidence, it is not accurate.

A source can be credible but irrelevant. Does it actually answer your specific research question? Or is it just about your general subject? Be ruthless. If it doesn’t support your thesis, don’t use it.

Check the publication date. Is it recent enough? In fast-moving fields like STEM or computer science, a source older than 5-7 years may be outdated. In the humanities (e.g., history, literature), an older source may be foundational.

The CRAAP Test Explained

Use these 5 questions to evaluate sources.

Sources to Avoid (Red Flags)

Not all sources are equal. Avoid these.

• Wikipedia: Do not cite Wikipedia. Do use the “References” section at the bottom of a Wikipedia article to find the *real* academic sources.
• Blogs & Forums: These are opinions, not evidence. (e.g., Reddit, Quora).
• Advocacy & Political Sites: These sources have a clear bias. Their goal is to persuade, not inform.
• Sources with No Author: If no one claims it, you can’t trust it.
• Sources with No Citations: If they don’t show their work, you can’t verify their claims.