A valid assessment is one which measures what it is intended to measure.

For example

...it would not be valid to assess driving skills through a written test alone.

A more valid way of assessing driving skills would be through a combination of tests that help determine what a driver knows, such as through a written test of driving knowledge, and what a driver is able to do, such as through a performance assessment of actual driving.

Teachers frequently complain that some examinations do not properly assess the syllabus upon which the examination is based; they are, effectively, questioning the validity of the exam.

Reliability...

Reliability relates to the consistency of an assessment.

...a reliable assessment is one which consistently achieves the same results with the same (or similar) cohort of learners. Various factors affect reliability - including...

• ...ambiguous questions,
• ...too many options within a question paper,
• ...vague marking instructions and
• ...poorly trained assessors.

...has both validity and reliability.

In practice, an assessment is rarely totally valid or totally reliable. A tape measure or set of scales which are incorrectly calibrated will always give the same (wrong) measurements. They are very reliable, but not very valid.

- Validity.mp3 - Reliability.mp3 - Good Assessment.mp3 .

(Note: this page was made using three Free Text iDevices; embedding MP3 files with player and attaching files for download; Online resources, like this can support different learning styles and provide self-paced learning. Use of audio files can support the development of conceptual learning. The audio files were produced using Audacity - http://audacity.sourceforge.net/ however SwiffRec - http://www.snapfiles.com/get/swiffrec.html is in many ways a simpler option)