There Is No Such Thing as a Valid Test

Dr. Dylan Wiliam

All those who produce tests claim that their tests are valid and reliable. Unfortunately, such claims are meaningless, because tests cannot be valid, and they cannot be reliable.

A failure to understand why such claims are incorrect means that the substantial power of assessment to support learning is often lost.

In this week’s webinar, Dylan Wiliam explained how to think about validity and reliability in a way that means that our assessment practices can both support learning and provide meaningful information about our students.



Dr. Wiliam couldn’t get to all of the viewers’ questions before the time was up. However, he has responded to the remaining questions, and we’re pleased to share the audio:

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