Definition of Tests & Measures
Several disciplines gain research data through a survey or questionnaire to quantify subject responses and measure them according to a scale. They are rigorously developed within discipline standards to be valid and reliable research instruments.
They are also called scales, measures, or tests. Researchers can develop unique instruments for a particular study or borrow from another study that has a broadly applicable one. Some instruments become well-known and often used or modified.
The American Psychological Association divides research instruments (questionnaires, scales, surveys, tests, measures, etc.) into two broad categories - "published" (commercial) and "un-published" tests.
"Published" tests are formally published. Generally they are only available from a commercial publisher for a fee. You can identify published tests through Mental Measurements Yearbook/ Tests in Print, which includes contact information for the copyright owner. Also, ETS Test Link indexes 25,000 educational tests, including contact information for published tests and citations to articles where unpublished tests.
"Unpublished" or "Non-Commercial" tests may be available for you to use (contact the author). They are sometimes reproduced in books or academic journal articles. See above tab for Compilations of non-commercial tests. You can identify them through searches in databases or catalogs, sometimes limiting your topic with additional keywords such as "test", "measure", "scale" or using a filter for "empirical study" in some database advanced search features, such as PsychInfo.
For more information, see the APA's guide to Finding Information About Psychological Tests.