Here are some especially-good articles from third-parties about assessments. (Note: These links will open in a new window and you will be leaving the Pearson website.)
The New Science of Hiring (Inc.com)
The Incredible Cost of a Bad Hire (ere.net)
Whether or Not You Realize it, You're Using Assessments (ere.net)
Web-based Assessments Aid the Employee-hiring Process (HROtoday.com)