The most widely used test to assess personality traits is the:

The Minnesota Multiphasic Personality Inventory-2 (MMPI-2) is indeed the most widely used test for assessing personality traits, particularly in clinical settings. This assessment tool is specifically designed to evaluate various psychological conditions and personality structure. Originally developed in the late 1930s and extensively revised, the MMPI-2 features a comprehensive set of true or false statements that help identify personality attributes and potential psychological issues.

The MMPI-2 is distinguished by its empirical foundation; it was developed using a criterion-keyed approach, which ensured that items measure distinct psychological conditions effectively. This has led to its widespread acceptance in various fields, including psychology, psychiatry, and counseling, making it a cornerstone for personality assessment.

Other options, while notable, serve different purposes or are utilized in more specialized contexts. For instance, the NEO-PI assesses the five major domains of personality based on the Five Factor Model but is not as broadly used as the MMPI-2. The 16 Personality Factor Questionnaire (16PF) is another well-respected tool, providing a comprehensive assessment of normal personality traits rather than clinical conditions. Lastly, the California Psychological Inventory (CPI) focuses on interpersonal behavior and social interactions. Each of these instruments has its