Tests are a standardized measurement instrument.  They may be called an inventory, questionnaire, index, scale, checklist, profile or a test. They are often used in Psychology and related fields (Education, Child and Youth Studies, Disability Studies, Business, Neuroscience and other behavioural sciences).  "Commercial" tests are licensed, copyrighted and may include restricted access or a fee. "Unpublished" tests are more readily accessible in the literature. This guide provides you with resources for finding and learning more about both types.  You will also find resources for how to conduct such tests in your own research.