Quadrant theory became the basis for many personality tests. This type of testing establishes polar opposites (for example, introverted vs. extroverted, rational vs. emotional, logical vs. intuitive, etc.) and attempts to place people along a spectrum. Combining these traits allows personalities to be studied in two- or three-dimensional maps. Marston’s test, for example, posits four types of behavior: dominance, influence, steadiness, and conscientiousness, for which it has become known as the DiSC test. Similarly, other popular personality tests, such as the Myers-Briggs Type Indicator and the Keirsey Temperament Sorter, have their roots in quadrant theory. But do these tests actually work? There are now hundreds, perhaps thousands, of personality tests available, and they vary in their scientific rigor and validity. Reputable, scientific tests certainly exist, and countless firms have used them to great success. However, before using any test for professional reasons – whether taking it yourself or asking your employees to take it – you should always do your homework. Here are a few guidelines: Did you discover the test through a prominent feature on a popular consumer website, such as AOL, MSN, or Yahoo? If so, it is probably not a good choice for your workplace. These types of tests are usually for entertainment purposes. Was the test designed by a Ph.D. in psychology? Is the test free? If so, be wary. Scientific rigor is rarely free. Who is administering the test? The administrator should be able to help you understand the test results and apply them to your workplace. Most experienced consultants and professional services firms offer this service.