DISC assessment
DISC is a group of psychometric tests based on the 1928 work of psychologist William Moulton Marston.

# History
DISC is the four quadrant behavioral model based on the work of William Moulton Marston Ph.D. (1893 - 1947) to examine the behavior of individuals in their environment or within a specific situation. DISC looks at behavioral styles and behavioral preferences.
Marston completed doctoral studies at Harvard in the newly developing field of Psychology. In the early 1920's Marston first studied the concepts of will and power and their effect on personality and human behavior. These findings contributed greatly to the field of psychology.
Marston published Emotions of Normal People in 1928. In this book he first formally presented his findings, though he had written about DISC four years earlier. Marston published a second book on DISC, Integrative Psychology, in 1931. Marston really wanted to develop a unit of measurement of 'mental energy'. He did not develop the DISC test or assessment. In fact, he never used it as an assessment at all. However, in 1930, a friend did use it as an assessment in a book on success and it was published as one of the first in the newly emerging field of Self-Help publications.

# Method
The tests classify four aspects of behavior by testing a person's preferences in word associations (compare with Myers-Briggs Type Indicator). DISC is an acronym for:
- Dominance - relating to control, power and assertiveness
- Influence - relating to social situations and communication
- Steadiness (submission in Marston's time)- relating to patience, persistence, and thoughtfulness
- Conscientiousness (or caution, compliance in Marston's time) - relating to structure and organization
These four dimensions can be grouped in a grid with D and I sharing the top row and representing extroverted aspects of the personality, and C and S below representing introverted aspects. D and C then share the left column and represent task-focused aspects, and I and S share the right column and represent social aspects. In this matrix, the horizontal dimension represents a factor of "Assertive" or "Passive", while the vertical represents "Open" vs. "Guarded". 
- Dominance: People who score high in the intensity of the 'D' styles factor are very active in dealing with problems and challenges, while low D scores are people who want to do more research before committing to a decision. High "D" people are described as demanding, forceful, egocentric, strong willed, driving, determined, ambitious, aggressive, and pioneering. Low D scores describe those who are conservative, low keyed, cooperative, calculating, undemanding, cautious, mild, agreeable, modest and peaceful.
- Influence: People with High I scores influence others through talking and activity and tend to be emotional. They are described as convincing, magnetic, political, enthusiastic, persuasive, warm, demonstrative, trusting, and optimistic. Those with Low I scores influence more by data and facts, and not with feelings. They are described as reflective, factual, calculating, skeptical, logical, suspicious, matter of fact, pessimistic, and critical.
- Steadiness:(Submission in Marston's time): People with High S styles scores want a steady pace, security, and don't like sudden change. Low S intensity scores are those who like change and variety. High S persons are calm, relaxed, patient, possessive, predictable, deliberate, stable, consistent, and tend to be unemotional and poker faced. People with Low S scores are described as restless, demonstrative, impatient, eager, or even impulsive.
- Conscientious: (Compliance in Marston's time): Persons with High C styles adhere to rules, regulations, and structure. They like to do quality work and do it right the first time. High C people are careful, cautious, exacting, neat, systematic, diplomatic, accurate, tactful. Those with Low C scores challenge the rules and want independence and are described as self-willed, stubborn, opinionated, unsystematic, arbitrary, and careless with details.
A common general public misconception is that if one is described as having either a D, I, S, or C style that all people are simply categorized into one of four types. The 1970's work by Dr John Geier brought DISC into practical application with substantive research. The Geier research delineated the distinct differences of persons within the 4 factor styles with the advent of the Classical Pattern definitions. It was found that there are distinct differences between persons within each of the 4 style profiles. For example not all D's behave in the same way. The same is accurate for the other styles of behavior.

# The Success Insights Wheel
The DISC styles have been broken down further into a colorful wheel divided into eight parts. The four core DISC types plus four blends with adjacent types are given names, with their brief descriptions:
- Conductor - Core D - direct and results-oriented
- Persuader - Core D, influenced I - optimistic and flexible
- Promoter - Core I - verbal and trusting
- Relater - Core I, influenced S - cooperative team player
- Supporter - Core S - accommodating and persistent
- Coordinator - Core S, influenced C - cautious and self-disciplined
- Analyzer - Core C - precise and detail-oriented
- Implementer - Core C, influenced D - creative and indecisive
The wheel consists of five concentric rings. The eight "descriptive styles" lie on the outer ring, numbered 1-8. The next three rings consist of 16 segments each, numbered from 9-24, 25-40 and 41-56 respectively, where you can have even further blended types such as a "Conducting Persuader" (#12), or an Implementing Analyzer (#23). The third ring in will consist of the same blends, but considered "flexible" types. The inner ring only has four quadrants, numbered 57-60, corresponding to the original pure types only. (In the sample reports given, nobody scores in these two inner rings).  The wheel plots both the person's Natural Style and Adapted Style.
It is also used with the PIAV "Six Attitudes". 
These are said to measure the "WHY" of behavior, where DISC is measuring the behavior itself.   . There is also another version of the Insights wheel with different names.