A contributor's credentials should relate to your subject. A credible blogger might:

• Have a degree, do scholarly research or work in this field
• Be part of a group or organization with relevant goals
• Have demonstrated knowledge of this subject (e.g., author of a book)

Every author has opinions and a worldview that shape his or her treatment of a subject. As you read the blog post, ask yourself how the author's views and affiliations might affect the presentation or omission of information.